A man of about 18 who was sleeping with headphones and travelling from Edmonton to Winnipeg was set upon by his seat mate just before 10 p.m. Wednesday.
He was stabbed repeatedly with a large hunting knife, sending blood spraying across the interior of the bus. The driver quickly pulled over and passengers fled out the front door.
The attacker then sawed off the victim's head and carried it to the front of the bus.
The two did not apparently know one another. The victim boarded the bus in Edmonton, one witness said, and the attacker boarded in Manitoba, CTV reported..
A standoff with police ensued until about 1 a.m. local time.
A 40-year-old man was taken into custody.
Garnet Caton, 26, was sitting in the seat in front of the attacker.
"I was just reading a book and all of a sudden I heard a guy screaming. I turned around and the guy sitting right beside me was standing up and stabbing another guy with a big Rambo knife," he said.
"Right in the throat. Repeatedly."
The man wielding the knife had a shaved head and was wearing sunglasses, he said.
"He looked totally calm. He didn't say a word I don't think to anybody on the bus ... nothing. Just totally calm."
Caton said most passengers were sleeping at the time and didn't realize what was happening.
"I screamed 'stop the bus!' ... Everybody got the hell off, and people at the front of the bus didn't really understand what was going on. It almost turned into a trample scene there, everybody trying to get off the bus. But the guy didn't care at all. He wasn't concerned with anybody but the guy he was stabbing.
"The guy was totally calm. When he brought the head he looked at us and dropped it. It was like he was having a day at the beach. He couldn't be bothered by anything else."
Passenger Cody Olmstead from Kentville, N.S., said he had just smoked a cigarette with the victim at the last stop in Brandon. He said he believed the victim had gotten on the bus in Edmonton.
"We just left the town of Brandon and we were watching Zorro and the next thing I know I hear somebody scream and I look back and there's some big guy holding this little fellow up between the bathroom door and the seat," Mr. Olmstead told CBC News.
After passengers fled the bus and braced the door to keep the attacker inside, he returned with the victim's head, Olmstead said.
"His hand come out the door with the knife," he said. "He went back on the bus and then they [passengers] brace the door and he come back standing in the doorway with the head, looked at them, dropped the head, went back and started cutting buddy back up."
As night fell and police surrounded the bus, the suspect taunted police officers, Olmstead said.
"He comes up and he picks the head up and he's waving it in the window. I just smoked a cigarette with this man [the victim] earlier, the head, and he's shaking it back and forth at the window and it's ... intense right, it's sickening."
RCMP Sgt. Steve Colwell provided few other details at a press briefing Thursday afternoon. He referred to the crime as a stabbing, but refused to confirm whether or not the victim had been decapitated. Sgt. Colwell said the suspect was arrested just before 1:30 a.m. when he tried to escape through a broken bus window after a prolonged standoff with police.
Sgt. Colwell said the suspect, who has yet to be charged, is believed to have been from out of province. He refused to name him or the victim. He also refused to confirm the victim's age or where he is from.
Public Safety Minister Stockwell Day said the violent attack is a "horrific" incident and his heart goes to the family of the victim.
However, Day played down the possibility of enacting tough security measures in Canada's bus terminals, similar to what already exists in airports.
"People should always be open to looking at precautionary measures. But let's keep in mind that as bizarre and tragic as this is, it is extremely rare," Day said.
He also dismissed talk by some opposition MPs of a "knife registry," saying that millions of them are bought each year simply for kitchen use. He added that there are already provisions in the Criminal Code against crimes and assaults.
Speaking at a Conservative caucus meeting, Mr. Day said he does not want to jeopardize the investigation, but added he wants to see the killer "convicted in court."
"We want to make sure that the process is followed as aggressively as possible, a full legal process, and the perpetrator is definitely dealt with the full force of the law," he said.
Greyhound called the event tragic but isolated.
A company spokeswoman said bus travel is the safest mode of transportation, despite the fact bus stations do not have metal detectors and other security measures used at airports.
"Due to the rural nature of our network, airport-type security is not practical. It's a very different type of system," Abby Wambaugh said from Greyhound's corporate offices in Texas.