Seven people were injured when fire broke out at an Oliver apartment complex Sunday morning.

One adult and the child, estimated to about six years old, are in serious condition at the University of Alberta Hospital.

The CBC's Ann Sullivan reported that about 60 firefighters and at least a dozen fire trucks were called to the scene, which was immediately declared to be a two-alarm fire but quickly escalated to a three-alarm fire.

One of the truck’s aerial ladders was extended up to the building’s eighth floor and was used to remove at least one of the building’s injured residents.

The extremely hot fire caused extensive damage to multiple suites on the building’s eighth storey, with some additional damage spreading to the ninth storey, said one fire official.

Firefighters successfully evacuated the building. About 80 people gathered in the gymnasium of Oliver School across the street. 

Fire officials say the residents will receive care from the Red Cross for 72 hours.

The cause of the fire is still under investigation.