Fire crews had to launch an aggressive attack to get control of a fire that ripped through an apartment complex in Mission on Tuesday morning.

Firefighters were called to the complex at 2204 1 Street S.W. at about 5:15 a.m. and encountered a large volume of smoke billowing from the top of the building when they arrived.

Crews quickly called a second alarm and evacuated the residents from all 66 units.

Four units were completely destroyed in the fire and several others suffered smoke and water damage.

Fire officials say the investigator has finished his assessment and has determined the blaze was started by smoking material that was put into a planter pot.

Alana Chypyha says her unit was badly burned. "Pretty much, he woke up and we just grabbed our cat and our hedgehog and we got out. Our screen door was in flames, we probably got out just in time."

Stephanie Cormier lives on the second floor and says she woke up and heard the alarm going off and someone running upstairs.

"I just got up and opened my door and saw the fire shooting out of one of the balconies. I basically just got my cat and ran out. By the time I was out, the flames were just shooting out. It was crazy."

Paul LeBlanc, with the Calgary Fire Department, says all the occupants of the building were accounted for and many were not home at the time.

“This side of the building is going to be completely affected so they’re not going to be allowed back into their suites for quite a while, it looks like, so they will have to make alternate arrangements,” said LeBlanc.

About ten trucks, along with 50 firefighters were called to the scene to battle the blaze.

Structural engineers have been called in to assess the integrity of the building and ATCO and ENMAX crews are also on scene.

Residents are being allowed in to retrieve valuables in areas of the building that were not as heavily affected by the fire.

Officials say residents will not be allowed to move back in until all utility and fire and life safety systems are restored, which could take several days.