Canada's biggest city entered lockdown on Monday in the latest bid to curb coronavirus infections, with case numbers surging across North America even as US officials said vaccinations could be available within weeks.

Six passengers were injured on Monday during an emergency evacuation of their Canadian WestJet flight, which was diverted to Winnipeg following a "threat."

The Boeing 737 was diverted on its way between Edmonton in the western part of the country to Toronto following the threat, WestJet reported on its Twitter account, without providing details.

Toronto police said Monday they now know who dug a tunnel near a major sporting venue in Toronto -- a mystery that has been a source of widespread speculation and conspiracy theories.

In a statement, police said two young men stepped forward to acknowledge responsibility after authorities made a public plea for help to determine its purpose.

The trial of two men accused of plotting to derail a Toronto-New York passenger train to protest the deployment of Western troops in Afghanistan started Monday in Canada.

Chiheb Esseghaier and Raed Jaser, both in their 30s, were arrested in 2013 in what police said was an al-Qaida-backed plan to sow fear across North America.

The North American Aerospace Defense Command scrambled two CF-18 fighter jets out of Quebec Wednesday to escort Sunwing Flight 656 back to Toronto after a "passenger disturbance," a spokeswoman said. 

Four people were injured Wednesday morning in a stabbing rampage at an office park in the Canadian city of Toronto, police said.

Toronto police Constable Jenniferjit Sidhu said "a person armed with scissors or a knife" burst into a fifth floor office in a building in the city's north end.

Police shot and killed an armed man at Canada's busiest courthouse on the outskirts of Toronto on Friday after he entered the secure building and shot and wounded an officer.

The unidentified shooter walked into the courthouse in Brampton, Ontario at about 11 am and "discharged a firearm," injuring the policeman, a special investigative unit said in a statement.

Two Paraguay filmmakers proved this week that a hit movie can be made on a small budget, with the international premiere of their crime thriller "7 boxes" (7 Cajas) at the Toronto film festival.

Directors Juan Carlos Maneglia and Tana Schembori's first feature film is the only one from Paraguay being screened at North America's biggest film festival.

A gunman opened fire Saturday in a busy food court at one of Canada's best known shopping malls, Toronto's Eaton's Centre, killing a 25-year-old man and leaving seven others injured, police said.

"The nature of the wounds indicate this individual was targeted," said Toronto police chief Bill Blair. "The others were innocent bystanders."

A Canadian Via Rail passenger train derailed west of Toronto Sunday, killing three railroad employees and injuring dozens of passengers, officials said.

Via Rail spokeswoman Michelle Lamarche said the three people killed were all engineers riding in the cab of the locomotive at the front of the train when it derailed in Burlington, Ontario. A fourth Via worker in the locomotive was injured, she said.