A man on a Greyhound bus travelling across the Canadian Prairies has killed and decapitated a fellow passenger.
An eyewitness said the victim was stabbed 50 or 60 times by the man sitting next to him, who then severed his head with a large knife.
The driver pulled over and passengers fled from the bus, bracing the door to keep the attacker inside.
A 40-year-old man was arrested after a standoff lasting several hours and is in police custody.
The attack appeared to be unprovoked and it is thought the killer did not know his victim.
The bus, with 37 passengers and a driver aboard, was travelling from Edmonton, Alberta, to Winnipeg, Manitoba.
"All of a sudden, we all heard this scream, this bloodcurdling scream," passenger Garnet Caton told CBC television. "The attacker was standing up right over the top of the guy with a large hunting knife holding the guy and continually stabbing him... in the chest area," he said.
The attack continued as passengers fled the bus and waited for police on a desolate stretch of the TransCanada Highway near Portage la Prairie in Manitoba.
Mr Caton, the bus driver and a trucker who had stopped at the scene boarded the vehicle to see if the victim was still alive. The attacker ran at them, Mr Caton said, and they ran out of the bus, holding the door shut to prevent him getting out.
The passengers were taken to a hotel in Manitoba where they received counselling.