Police have charged a bus driver with first-degree murder after he drove his vehicle at a high speed into a day care center north of Montreal, killing two children, injuring six and leaving authorities searching for a motive.

Witnesses say that after Wednesday's crash, the 51-year-old driver, identified as Pierre Ny St-Amand, stepped out of the bus, stripped off his clothes and started screaming.

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

A neighbor who ran to the center in Laval, Quebec, said she saw children screaming and crying and watched a mother collapse.

St-Amand is facing nine charges including first degree murder, attempted murder, aggravated assault and assault causing bodily harm. He appeared in court via video late Wednesday from a hospital room and will remain detained.

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.

The driver had worked for Societe de transport de Laval for 10 years. He 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.

Boyer said "there is a theory that it was an intentional act, but that remains to be confirmed by the investigation,

Laval Police Chief Pierre Brochet said authorities are interviewing the driver.

The dead children were both 4 years old, identified in the documents only by their initials. Six children were hospitalized with injuries that were not life-threatening, Brochet 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.

Sirois' wife, Ginette Lamoureux, the neighbor who ran into the day care shortly after the crash, said the driver was hysterical.

“His eyes were like popping out,” she said.

Benchaabane said he and three parents had to strike the driver in order to subdue him, before police cuffed him.

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

Members of Parliament observed a moment of silence in Ottawa.

Wearing a hospital gown and in a bed, St-Amand was alert but unresponsive during his video appearance as the judge and his lawyer tried to get him to speak. He only nodded his head a few times when asked by his lawyer, Julien Lespérance Hudon, if he understood he was appearing in a courtroom.

The case returns to court on Feb. 17.

Neighbors described the suspect as a quiet, pleasant father of two young girls. One man, Thanh-Ry Tran, said his family got together with the suspect’s family a few times a year, and their wives would sometimes help each other in picking up or dropping off children. He said the suspect had never shown signs of distress.

Another neighbor, Nader Abou-Said, said he would exchange pleasant greetings with the suspect, and would often see him playing with his daughters in the backyard.

“How can you go out and play with your kids and then go kill kids?” he said.