Latest: Details emerge about Texas serial bombing suspect who died in explosion

Update 5.03pm: The suspect in the deadly bombings that terrorised Austin, Texas, blew himself up as authorities closed in on him, but police have warned that more bombs could be out there.

The suspect's motive remained a mystery, along with whether he acted alone in the five bombings in the Texas capital and suburban San Antonio that killed two people and wounded four others.

Police zeroed in on the 24-year-old man in the last 24 to 36 hours and located his vehicle at a hotel on Interstate 35 in the suburb of Round Rock.

Officers were waiting for armoured vehicles to arrive before moving in for an arrest when his vehicle began to drive away, Austin police chief Brian Manley said at a news conference.

Officials work at the scene in the Austin suburb of Round Rock, Texas. AP Photo/Eric Gay

Authorities followed the vehicle, which ran into a ditch on the side of the road, he said.

When members of the Swat team approached, the suspect detonated an explosive device inside the vehicle, the police chief said.

The blast knocked one officer back, and a second officer fired his weapon, Mr Manley said.

A law enforcement official identified the dead man as Mark Anthony Conditt.

Authorities released few details about the suspect, except his age and that he was white.

But online postings indicate he was home schooled.

He later attended Austin Community College from 2010 to 2012, according to a college spokeswoman, but he did not graduate.

A blogger who identified himself as Mark Conditt of Pflugerville described his interests as cycling, tennis and listening to music.

In blogs dated from 2012, he wrote that gay marriage should be illegal and called for the elimination of sex offender registrations.

The mayor of Pflugerville, an Austin suburb not far from the site of the first of four bombings, said the suspect lived in his city, just two streets from his house.

Pflugerville resident Jay Schulze said he was jogging on Tuesday night when he was stopped by police and asked about the bombings.

He said police flew drones over a home for about six hours between Tuesday evening and early Wednesday morning.

Mr Schulze described the home over which the drones were flying as "a weird house with a lot of people coming and going" and a bit rundown.

A neighbour who watched the suspect grow up said he "always seemed like he was smart" and "polite".

Jeff Reeb said he has lived next to the parents of Conditt for about 17 years and that they are good neighbours.

Mr Reeb said Conditt and his grandson played together when they were younger and that Conditt still visited his parents regularly.

The parents live a few miles from the Pflugerville home where Conditt lived with roommates.

Mr Reeb said Conditt was in the process of gutting the house and remodelling it, which meant a lot of hammers and nails around frequently.

He said police had an unmarked car parked near Conditt's parents' house overnight into Wednesday.

Mr Reeb said Conditt's father, whom he called Pat, worked as an Amway distributor and also bought electronics on the side to resell.

Austin was hit with four package bombings starting on March 2.

A fifth parcel bomb went off early on Tuesday at a FedEx distribution centre near San Antonio.

Citing a high-ranking law enforcement official, the Austin American-Statesman reported that authorities had identified the suspect based largely on information, including security video, gleaned after he sent an explosive device from an Austin-area FedEx store.

Police warned on Wednesday of the possibility that more bombs had yet to be found.

"We don't know where this suspect has spent his last 24 hours, and therefore we still need to remain vigilant to ensure that no other packages or devices have been left to the community," Mr Manley said.

Authorities initially believed the bombings may have been hate crimes because the victims of the earliest blasts were black, but they backed off that theory after Hispanic and white victims from different parts of the city were also affected.

Fred Milanowski, an agent with the US Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), said it was "hard to say" if the bombing suspect had acted alone.

"What we do know is we believe the same person built each one of these devices," said Mr Milanowski, the agent in charge of the Houston division of the ATF.

Asked if the suspect built bombs before the Austin attacks, Mr Milanowski said: "We know when he bought some of the components. It's hard to say whether he was building along the way."

Austin mayor Steve Adler thanked law enforcement for their work in bringing down the suspect and urged residents to continue to report anything that appeared suspicious or out of place.

Isaac Figueroa, 26, said he and his brother heard sirens and helicopters early on Wednesday in the area and drove towards them, then cut through nearby woods on foot after they hit a police roadblock.

Mr Figueroa said they saw a silver or grey Jeep Cherokee that was pinned between black and white vehicles and "looked like it had been rammed off the road".

He said he saw police deploy a robot to go to examine the Jeep.

President Donald Trump, who had earlier said whoever was responsible for the Austin bombings was "obviously a very sick individual or individuals", tweeted: "AUSTIN BOMBING SUSPECT IS DEAD. Great job by law enforcement and all concerned!"

The suspect's death followed a day of rapid-fire developments in the case.

Early on Tuesday, a bomb inside a package exploded as it passed along a conveyor belt at a FedEx shipping centre in Schertz, north east of San Antonio and about 60 miles south west of Austin.

One worker reported ringing in her ears and was treated at the scene.

Later in the morning, police sent a bomb squad to a FedEx facility outside Austin airport to check on a suspicious package.

Federal agencies and police later said the package had contained an explosive that was successfully intercepted and that it too was tied to the other bombings.

The Schertz blast came two days after a bombing wounded two men on Sunday night in a quiet Austin neighbourhood about three miles from the FedEx store.

It was triggered by a nearly invisible tripwire.

Update 10.31am: Texas serial bombing suspect dies in explosion

The suspect in a spate of bombing attacks in Austin that have killed two people and injured four others this month blew himself up with an explosive device as authorities closed in, police said.

Authorities had zeroed in on the suspect in the last 24 to 36 hours and located him at a hotel on Interstate 35 in the Austin suburb of Round Rock, Austin police chief Brian Manley said.

They were waiting for ballistic vehicles to arrive when his vehicle began to drive away, Mr Manley said. Authorities followed the vehicle, which stopped in a ditch on the side of the road, the police chief said.

Texas troopers help redirect traffic near the site of another explosion yesterday. Pic: AP Photo/Eric Gay

When members of the Swat team approached, the suspect detonated an explosive device inside the vehicle, the police chief said. The blast knocked back one officer, while a second officer fired his weapon, Mr Manley said.

The suspect, who suffered significant injuries from the blast, was killed. Authorities identified him only as a 24-year-old white man.

Authorities said it was too soon to say if the suspect had worked alone. They also said they do not know his motive.

Earlier on Wednesday, the Bureau of Alcohol, Tobacco, Firearms and Explosives said federal and local authorities had converged on an area where the bombing suspect was holed up in the capital city.

Police in Austin tweeted that they were working an officer-involved shooting on Interstate 35.

On Tuesday, a bomb inside a package exploded at around 1am as it passed along a conveyer belt at a FedEx shipping centre in Schertz, north-east of San Antonio and about 60 miles south-west of Austin. One worker reported ringing in her ears and was treated at the scene.

Later in the morning, police sent a bomb squad to a FedEx facility outside the Austin airport to check on a suspicious package. Federal agencies and police later said that package had indeed contained an explosive that was successfully intercepted and that it, too, was tied to the other bombings.

Authorities also closed off an Austin-area FedEx store where they believe the bomb that exploded in Schertz was shipped. They roped off a large area around the shopping centre in the enclave of Sunset Valley and were collecting evidence.

The Schertz blast came two days after a bombing wounded two men on Sunday night in a quiet Austin neighbourhood about three miles from the FedEx store.

It was triggered by a nearly invisible tripwire, suggesting a "higher level of sophistication" than agents saw in three package bombs previously left on doorsteps, according to Fred Milanowski, the agent in charge of the Houston division of the US Bureau of Alcohol, Tobacco, Firearms and Explosives.

Authorities have not identified the two men who were hurt on Sunday, saying only that they are in their 20s. But William Grote told the Associated Press that his grandson was one of them and that he had what appeared to be nails embedded in his knees.

During an Oval Office meeting on Tuesday, President Donald Trump said whoever is responsible for the bombings "is obviously a very sick individual or individuals" and that authorities are "working to get to the bottom of it".

- APUpdate 9.05am: US media reports that the Texas serial bombing suspect has been killed.

It is believed the suspect was tracked down by police investigating a spate of bombings in the city of Austin.

The attacks have killed two people and seriously injured four others in recent weeks.

Earlier: Police in Texas say new explosion is not tied to others

Emergency teams have responded to another reported explosion in the capital of Texas - the sixth in the past three weeks.

Austin-Travis County Emergency Medical Services said a man in his 30s was injured - but police are not linking the explosion, caused by an artillery simulator, to others which have caused panic and deaths in the city.

Investigators are continuing to pursue a suspected serial bomber terrorising Austin for weeks and have uncovered what seemed like valuable new leads in the case.

The latest explosion, which went off yesterday, went off at a Goodwill store, and nearby stores and shopping centres were evacuated.

Gary Davis, president and CEO of Goodwill Texas, said the device was contained in a bag and detonated when a worker moved it.

"We put all the donations we get in a big cardboard box. He pulled something out in a bag, completely normal, and the device went off," Mr Davis said.

Even before the report of Tuesday evening's explosion, it had already been a busy day for authorities.

A bomb inside a package exploded around 1am on Tuesday as it passed along a conveyor belt at a FedEx shipping centre near San Antonio, causing minor injuries to a worker.

The Austin Police Department, the FBI and other federal agencies confirmed that the package centre blast was related to four previous ones that killed two people and seriously injured four others.

That explosion occurred at a FedEx facility in Schertz, just northeast of San Antonio and about 60 miles (95 kilometres) southwest of Austin.

Later in the morning, police sent a bomb squad to a FedEx facility outside the Austin airport to check on a suspicious package that was reported at around 6.20am.

Federal agencies and police later said that package had indeed contained an explosive that was successfully intercepted by authorities. They added that the intercepted package, too, was believed to be related to the other bombings.

Michael McCaul, a Republican from Austin who is chairman of the House Homeland Security Committee, said that investigators have obtained surveillance videos that "could possibly" show a suspect, but are still poring through video.

"I hope his biggest mistake was going through FedEx," Mr McCaul, who has spoken to federal investigators and Austin police Chief Brian Manley, said of the bomber.

He added that the person responsible for the bombings had previously been "very sophisticated in going around surveillance cameras".

"They've got a couple of videos that could possibly be the person but they're not sure at this point," he said.

Before it exploded, the package had been sent from Austin and was addressed to a home in Austin, Texas Attorney General Ken Paxton said.

In a statement, FedEx officials said the same person responsible for sending the package also shipped a second parcel that has been secured and turned over to law enforcement.

A company spokeswoman refused to say if that second package might have been linked to the one reported at the distribution centre near the airport.

The Schertz blast came less than two days after a bombing wounded two men Sunday night in a quiet Austin neighbourhood.

It was triggered by a nearly invisible tripwire, suggesting a "higher level of sophistication" than agents saw in three package bombs previously left on doorsteps, according to Fred Milanowski, the agent in charge of the Houston division of the Bureau of Alcohol, Tobacco, Firearms and Explosives.

Authorities have not identified the two men who were hurt in Sunday's explosion, saying only that they are in their 20s and white.

But William Grote said his grandson was one of them and that he had what appeared to be nails embedded in his knees.

On the night of the fourth bombing, one of the victims was riding a bike in the street and the other was on a sidewalk when they hit the tripwire.

"It was so dark they couldn't tell, and they tripped," Mr Grote said.

In Washington, President Donald Trump said the assailant behind the bombing is "very sick".

During an Oval Office meeting on Tuesday with Saudi Arabia's Crown Prince Mohammed bin Salman, the president said, "This is obviously a very sick individual or individuals," and authorities are "working to get to the bottom of it.

PA

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