A second-degree murder charge has been laid in the knife attack that left a Winnipeg bus driver dead.

Brian Kyle Thomas, 22, was arrested Tuesday following the stabbing death of Winnipeg Transit operator Irvine Fraser, 58. He has also been charged with possession of a weapon for dangerous purpose and failure to comply with a probation order.

Fraser, who went by his middle name, Jubal, pulled up to the last stop of his shift around 2 a.m. on Tuesday. He apparently had to ask the last rider to leave the bus, said the head of the Winnipeg Transit drivers' union.

"A scuffle ensued, a physical altercation, and it ended up outside the bus," said John Callahan, president of the Amalgamated Transit Union in Winnipeg.

According to police, who have reviewed video from security cameras on the bus, Fraser returned to the front of the bus but Thomas followed and said he didn't want to leave.

After repeated requests — "he was asked many, many times to exit the bus," police say — Thomas was physically escorted off by Fraser. The two men argued outside the bus and a fight erupted.

A 22-year-old man has been charged with second-degree murder in the knife attack that killed a Winnipeg Transit driver dead early on Valentine's Day. 2:22

"Sadly, things just escalated from that point," said police spokesman Const. Jason Michalyshen, adding that Fraser was stabbed multiple times in the upper body. "Even with the efforts of emergency personnel, he couldn't be saved.

"It's a very sad day for the City of Winnipeg when we have a civil servant doing their job, providing a service to members of the public. When they're confronted in this fashion, we're all taken aback by it.

"Our thoughts and prayers are with the family and the friends of the victim."

A 22-year-old man, Brian Kyle Thomas, has been charged with second-degree murder in the death of bus driver Irvine Fraser. (Meaghan Ketcheson/CBC)

Bloodstained snow was visible Tuesday as students walked past the scene, bordered by police tape and busy with homicide investigators.

Police were still on scene in the area as part of the investigation on Wednesday, Michalyshen said.

Fraser's death marks the first time a Winnipeg bus driver has been killed in an on-the-job assault, said Callahan.

Thomas was arrested not far from the scene, at a bend on the frozen Red River that runs adjacent to the University of Manitoba campus.

According to court documents, he has a long list of convictions in the past five years, including for at least three assaults, a robbery and threatening to injure or kill a woman.

Callahan has spoken to Fraser's wife, who is distraught and still recovering from the recent death of a daughter. She and Fraser were raising their granddaughter together and Fraser was considering retiring as early as next year, Callahan said.

A GoFundMe page has been set up by Winnipeg Transit colleagues to help Fraser's widow and family.

Callahan hopes Fraser's death leads to changes to make the job safer for drivers.

That starts with examining where some of the routes end, he said. Maybe they all need to wind up downtown, in a more central location where there is better security and an on-street inspector, Callahan said, to allow an extra person to be there to help wake a sleeper.

The U of M campus is far from downtown, dark and quiet at the hour Fraser pulled in at the end of his shift.

Besides cameras, city buses are equipped with emergency buttons that connect drivers to a 911 operator. Fraser didn't have a chance to push the button when he was attacked, said Callahan.

Winnipeg Mayor Brian Bowman said in a news conference Tuesday that he would reach out to Callahan to talk about safety improvements. Callahan said he is looking forward to that.

Protective shields were installed on some buses as an experiment a few years ago, after a surge in violent incidents against drivers, but they were dropped after the union surveyed drivers, who said they didn't like the design and found them cumbersome.

They also felt trapped because there was no alternative exit, such as on the left side of the driver.

Callahan believes what's needed is an entire redesign of transit buses — an idea that's being studied in the United States — with a full enclosure for drivers and an emergency door on the left.