OTTAWA — An afternoon commute in Canada’s capital turned to horror after a double-decker city bus became impaled on a passenger shelter, leaving three people dead and 25 injured, officials said.

Jim Watson, the mayor of Ottawa, said that one victim was standing on the platform at the time of the collision, and the other two were aboard the bus.

“Our hearts and condolences go out to all those who were injured,” Mr. Watson said at a news conference. “Our focus now must be to provide care and sympathy for those affected by the accident.”

Of the injured, 14 arrived at hospitals in critical condition.

It was the second deadly accident involving a double-decker bus in the city in less than six years.