Canada is coming to terms with one of the worst murders in its history as police seek to explain why a young man was decapitated by his neighbour on a Greyhound bus.

The man suspected of the gruesome attack on Tim McLean, a 22-year-old fairground worker, was charged with murder today.

Mr McLean was travelling home to Winnepeg when he was stabbed up to 50 times by the man sitting next to him.

Vince Weiguang Li, 40, was arrested on suspicion of murder on Thursday morning after a stand-off lasting several hours. He remained in police custody today.

Witnesses say they heard no conversation between Mr McLean and his attacker before a “blood curdling” scream was let out. It appears to have been a random attack as no connection has yet been made between the two men.

Garnet Caton, who was sitting in the seat in front of the victim, said Mr McLean was sleeping with his headphones on when he was attacked.

Mr Caton said he heard a “blood-curdling scream” and turned around to see the attacker in the seat behind him holding a large hunting knife and “continually stabbing him in the chest area.”

“He must have stabbed him 50 times or 60 times,” said Mr Caton, who screamed at the driver to stop the bus.

Mr Caton herded terrified passengers to the front of the bus before it pulled over and they fled screaming.

A passing lorry driver stopped to see what was happening. He boarded the bus with Mr Caton and the bus driver, armed with a tyre iron and tried to apprehend the knifeman. “When we came back on the bus, he was cutting the guy’s head off and pretty much gutting him up,” said Mr Caton.

Then the attacker turned and raced up the aisle towards them, and they retreated as the man began trying to slash them.

The killer then tried to start up the engine to drive off but the bus driver pressed a button to disable the engine before he could get away.

“While we were watching the door, he calmly walks up to the front with the head in his hand and the knife and just calmly stares at us and drops the head right in front of us,” said Mr Caton.

Police arrived on the scene about 10 minutes later and a four-hour standoff ensued.

The killer taunted police and walked back and forth inside the bus. At one point he held up the severed head for them to see. Bystanders retched at the sight.

Royal Canadian Mounted Police in Brandon, Manitoba said the attack took place around 8:30 p.m. on an eastbound Greyhound bus on the Trans-Canada Highway about 20 kilometres west of Portage la Prairie.

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