The bus collided with the platform at the Westboro bus station at about 3:50 p.m. ET, he said.
Three people died — two on the bus and one person waiting on the platform, Watson said. Twenty-three people were hurt and taken to hospitals, he said.
Ottawa Police Chief Charles Bordeleau said several people on the top section of the bus had to be freed.
He said investigators are trying to determine the cause of the crash. The driver was arrested and was being questioned by police, but the chief didn’t provide details.
OC Transpo, which is in charge of Ottawa’s public transportation, tweeted on its verified account, “Buses are being detoured as a result” of the collision.
The Ottawa Police Service Collision Investigation Unit arrived to investigate the incident. Bordeleau said the Ottawa Paramedic Service and Ottawa Fire Services worked the scene in partnership with the Ottawa Police.
Authorities asked people to avoid the area. Video from CNN partner CTV News showed multiple emergency vehicles at the Westboro Station.