Murdered PC's family praises life-saving efforts of helpers

One witness suggested the officer might have unwittingly allowed the attacker behind Parliament's gates as he tried to shelter fleeing civilians from harm.

Police said they now believe the marauding knifeman acted alone, adding that while they were investigating why he carried out the atrocity, "that secret may have died with him".

Masood drove his car along the bridge at speed, mowing down pedestrians, and was shot dead by police after he stormed the parliamentary estate on Wednesday afternoon.

A US tourist told the Mail on Sunday his terrified family had been ushered to safety by a police officer as Masood wrought destruction on Westminster Bridge.

But he added the officer's bid to protect the innocent in a secure zone could have allowed the killer to follow them through an open gate.

Dr Jay Morris, who was visiting the capital with wife Jilan Liu and niece Zoe, told the paper: "He saw these people rushing at him and he was trying to give them some protection because he knew something was going on; he'd heard a car crash, screaming people running by.

"He opened the little gate to let people in.

"He was not on guard for anything violent because he was helping people and it (would have) made him more vulnerable to attack because he was the first uniform the attacker saw when he came round the corner - he ran in a few seconds after Jilan and Zoe."

The family said they could not be sure it was PC Palmer who saved them, but Dr Morris added: "I think it is the same guy."

Security at the Palace of Westminster came under renewed scrutiny after footage showed a vehicle entrance to New Palace Yard had been left open during the attack and its immediate aftermath.

Dr Morris said the decision to open the gates could have saved lives.

"There would have been no place to go and he would have started hurting people," he said.

Hero MP Tobias Ellwood was among those who tried to save Pc Palmer's life after Masood had fatally wounded him.

Addressing those who helped, the officer's family said: "There was nothing more you could have done."

In a statement released on Saturday night they said: "We have been overwhelmed by the love and support for our family, and most especially, the outpouring of love and respect for our Keith.

"We want to thank everyone who has reached out to us over the past few days for their kindness and generosity.

Here is the full statement from the family of Pc Keith Palmer: pic.twitter.com/8wqhN3fvKU

— PA Media (@PA) March 25, 2017

"The police have been a constant, unwavering support at this very difficult time. It has made us realise what a caring, strong and supportive family Keith was part of during his career with the police. We can't thank them enough.

"We would also like to express our gratitude to the people who were with Keith in his last moments and who were working that day. There was nothing more you could have done.

"You did your best and we are just grateful he was not alone. We care about him being remembered for his selfless bravery and loving nature. We miss him so much, but we are also incredibly proud of Keith."

Police have released specific timings of Masood's murderous spree, showing he took just 30 seconds from mounting the pavement on the bridge to crashing into the perimeter fence at Parliament.

Within less than a minute he made his way on to the parliamentary estate, attacked PC Palmer, and was shot.

Deputy Assistant Commissioner Neil Basu, the senior national co-ordinator for UK counter-terrorism policing, said: "We still believe that Masood acted alone on the day and there is no information or intelligence to suggest there are further attacks planned.

"Even if he acted alone in the preparation we need to establish with absolute clarity why he did these unspeakable acts to bring reassurance to Londoners, and to provide answers and closure for the families of those killed and the victims and survivors of this atrocity.

"We must all accept that there is a possibility we will never understand why he did this. That understanding may have died with him."

He said officers were working to establish whether Masood was "a lone actor inspired by terrorist propaganda or if others have encouraged, supported or directed him".

He added: "Whilst the attack lasted only 82 seconds it will remain in the memories of many forever."

Counter-terrorism officers have spent days piecing together what led the 52-year-old to shed his birth name and later unleash carnage on the capital.

Only one man, 58, arrested in Birmingham remains in police custody after a 27-year-old man was released with no further action on Saturday.

A total of 11 people were initially held after raids across the country.

The Saudi Arabian embassy in London said Masood worked in the country, home to some of the most virulent Islamic extremism, for several years, raising the possibility he was radicalised overseas.

A childhood friend of the man then known as Adrian Elms told The Sun newspaper he first emerged as a Muslim after serving a jail sentence.

His abrupt religious conversion will fuel concerns about the rising threat of criminals being brought under the influence of hardened jihadists while in prison.

Masood's victims included US tourist Kurt Cochran and his wife Melissa who were on the last day of a trip celebrating their 25th wedding anniversary. Mr Cochran was killed and Mrs Cochran was badly injured.

Aysha Frade, believed to be a 43- year-old married mother of two, also died, along with retired window cleaner Leslie Rhodes.

Two people remain in hospital in a critical condition, one with life-threatening injuries.

Police said armed patrols would take place around Wembley Stadium and extra officers would be at the ground when England played a World Cup qualifier against Lithuania on Sunday.

There will also be a minute's silence before the 5pm kick-off.