The 269 is a "connexion route", operating during morning and evening rush hour, taking people between Mackenzie King station in the capital's downtown and Pinehill/Stonehaven station in Kanata.
Buses are being detoured from the area so that police officers can conduct an investigation.
"It is with deep sadness that I report there were three confirmed casualties, two of which were on the bus and one that was on the platform", Ottawa Mayor Jim Watson told reporters at a news conference late on Friday. "I want to express my sorrow and condolences of the Ottawa police service and other emergency services". He was in his apartment across the street from the station when he started hearing sirens just after 4 p.m. The driver of the bus was "detained on the scene and will be questioned at our police station", Bordeleau said.
An obviously distressed woman was seen being wheeled away from the bus on a stretcher by paramedics. "I saw one person being lowered from the top floor in a seated position".
"Based on the way it looked, if there was anybody at the front of the bus at the top ..."
Fourteen of the injured are in critical condition, according to Miles Cassidy, the chief of Ottawa's paramedic services. The double-decker bus appears to have crashed into the roof that hangs over the platform at the station.
Comatose woman hospitalized after birth with baby
That same year, a woman in a coma at a home in MA gave birth to a baby girl prematurely and with severe brain damage. Earlier this week, the chief executive of the corporation in charge of the home resigned over the case.
"I haven't seen something of this magnitude before", he said.
"You get a knot in the pit of your stomach".
Ontario Premier Doug Ford took it to Twitter to send a message to the victims and their families.
The Canadian PressOttawa Mayor Jim Watson described the incident at Westboro station as "horrific" on Twitter. "I have asked staff to ensure all necessary resources are made available to assist them through this hard time".
Photos and video from the scene showed emergency responders treating a number of people on the ground, as others used ladders to unload passengers trapped on the bus' upper level.