Two children have died and six more have been taken to hospital after a bus crashed into a nursery in Quebec, Canada.
Police in Laval, north of Montreal, said the bus driver was arrested and charged with homicide and careless driving.
Police set up a large perimeter around the building in Laval, and panicked parents who ran to the centre were diverted to a nearby school.
Dozens of police and emergency vehicles lined the blocked-off road leading to the nursery.
The driver is a 51-year-old man who had worked for Societe de transport de Laval for 10 years, and who had no criminal history and a clean work record, police officials and Laval mayor Stephane Boyer said at two separate news conferences.
“As of now, we don’t know the motive for the crime,” said police spokeswoman Erika Landry.
She did not say why police determined the crash to be a homicide and did not release the driver’s name.
Laval police chief Pierre Brochet said police are interviewing the driver.
“There is a theory that it was an intentional act, but that remains to be confirmed by the investigation,” the mayor said.
The six children who were taken to hospital had injuries that were not life-threatening, said Mr Brochet.
A senior Canadian government official said the crash was not a terrorist act and did not pose a threat to national security.
A man who lives near the nursery said he rushed to the scene of the crash and that he and three parents managed to subdue the driver, who he said stepped out of the bus, removed all his clothing and started screaming.
“The first thing he did was take off all his clothes after opening the bus door. He was just yelling; there were no words coming out of his mouth,” said Hamdi Benchaabane.
The nursery is located at the end of a driveway off a cul-de-sac.
There is a bus stop on the cul-de-sac, but the driver would have had to veer off the road and head down the long driveway to hit the building.
Mr Benchaabane said he and the others had to strike the driver to get him under control, before police handcuffed the man. The driver, he said, “was in a different world”.
Mr Benchaabane said he was able to help pull one child from the nursery, adding that he and the others tried to save a second child before firefighters ordered them to leave because pieces of the roof were at risk of falling.
“It was a nightmare, I can’t believe it,” he said of what he witnessed. “It was horrible.”
Aerial news footage from the scene showed the bus crashed into the front of the nursery.
Prime Minister Justin Trudeau said his office was “following the situation closely”.