Ottawa police are responding to what they called a "serious bus collision" at Westboro Station on the Transitway late Friday afternoon, with several people critically injured.
"The Ottawa Police Service Collision Investigation Unit is also on scene and will be investigating this incident", read an earlier release from police. The driver was questioned by police, he said.
There were three people killed in total - two on the bus, one on the platform.
He said investigators are trying to determine the cause of the crash.
An obviously distressed woman was seen being wheeled away from the bus on a stretcher by paramedics. After 5 p.m., the Ottawa Hospital had said that nine people were in in critical condition, however Ottawa paramedics said several are in serious condition as of the 7 p.m. City of Ottawa news conference.
Gabe Rivett-Carnac arrived at Westboro station on a double-decker bus himself about an hour before the crash.
The incident occurred just before 4 p.m. on Friday, according to Ottawa police.
He went outside and came across a "chaotic" scene, with at least 30 emergency vehicles, including seven or eight fire trucks, and lots of police and bystanders, he said.
"Based on the way it looked, if there was anybody at the front of the bus at the top".
"I haven't seen something of this magnitude before", he said.
"I saw bodies flying out and it was pretty intense at the time", Borle said. "It's not a comfortable thing to witness and I can't imagine experiencing it".
Ottawa Mayor Jim Watson tweeted he was shocked to hear of the "horrific incident".
The Canadian PressPolice said a double-decker bus collided with a transit shelter at a busy station west of downtown Ottawa.
"Such devastating news. My thoughts and condolences are with the victims, their families and all those affected by this tragedy", wrote Environment Minister Catherine McKenna, who represents the area in Parliament. "I have asked staff to ensure all necessary resources are made available to assist them through this hard time". Video from CNN partner CTV News showed multiple emergency vehicles at the Westboro Station.