US bus giant Greyhound has now confirmed that 10 people were killed when a passenger slit a driver's throat, causing the vehicle to crash.
The attacker and the driver are thought to be among the dead.
There were 32 other passengers on the bus - but there are fears that the death toll may rise as the bus turned over and there could be passengers trapped underneath.
Greyhound has suspended all services across the US as a precautionary measure.
US officials have said the crash was unrelated to the attacks on the World Trade Center and the Pentagon on September 11 and called the crash a 'random incident'.
It is unclear whether US President George Bush, who is in New York today, has been made aware of the incident.