A city bus crashed into a day care center north of Montreal on Wednesday, leaving two children dead and sending six to the hospital, authorities said. The bus driver was arrested and charged with homicide and careless driving.

Police set up a large perimeter around the building housing the day care in Laval, Quebec, and panicked parents who ran to the center were diverted to a nearby elementary school. Dozens of police and emergency vehicles lined the blocked-off road leading to the day care.

An eyewitness said that immediately after the crash, the driver stepped out of the bus, ripped his clothes off and started screaming.

"He was just yelling; there were no words coming out of his mouth," said Hamdi Benchaabane.

The driver is 51, had worked for Societe de transport de Laval for 10 years, and had no criminal history and a clean work record, police officials and Laval Mayor Stéphane Boyer said at two separate news conferences.

"As of now, we don't know the motive for the crime," Police spokesperson Erika Landry said. She did not say why police determined the crash to be a homicide and didn't 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," Boyer said.

The day care 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.

"There were no signs of skidmarks. .... He went directly into the day care," said another eyewitness, Mario Sirois.

The six children who were hospitalized had injuries that were not life-threatening, Brochet said.

A senior Canadian government official said the crash was not a terrorist act and did not pose a threat to national security. The official spoke on condition of anonymity as they were not authorized to speak publicly on the matter.

Benchaabane, who lives near the day care, said he rushed to the scene of the crash and that he and three parents managed to subdue the driver.

He said they had to strike the driver to get him under control, before police cuffed the man. The driver, he said, "was in a different world."

Benchaabane said he was able to help pull one child from the day care, 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."

Brochet said officers at the scene were crying.

Prime Minister Justin Trudeau said his office was "following the situation closely."