Residents of a northwest Calgary apartment building had to be evacuated on Tuesday night after a fire broke out on the sixth floor.

Crews were called to a 17-storey apartment complex on Ulster Road at around 11:30 p.m.

Once they realized their task ahead, they had to call in reinforcements to help them get people to safety.

“The fire was contained to one unit on the sixth floor,” says Battalion Chief Don Huska.

Huska says that there were two people in that unit when the fire broke out and they were taken to hospital.

There is no word on their injuries.

Crews brought the blaze under control and everyone was allowed to return home, with the exception of the residents in the unit where the fire began.

The cause of the fire is under investigation.