Firefighters were called to a two-alarm fire in the Sunalta area on Monday evening that gutted a building that was under construction.

The fire broke out at about 7:35 p.m. at a property in the 1600 block of 16 Avenue SW.

Multiple fire units responded to the scene and officials say the building started to collapse shortly after crews arrived.

Emergency crews went door to door to ensure people living nearby were safe.

Brandon Sadler and Nadia Hamilton were watching a movie at a home a couple doors down when the fire broke out and say the blaze was well underway when they got outside.

“I go to the window and I look out and all I see is a big ball of fire up in the sky and I’m like, okay, yep let’s leave and so we quickly grabbed some stuff and ran outside and by the time we got out, there was already some EMS knocking on the condos beside us,” said Sadler. “As we came out, all the fire trucks came, police, EMS.”

“At first it was very anxiety inducing but seeing all the firefighters here, the police officers, they’re managing everyone, they’re talking to everyone, they’re calming everyone down so I mean, having their presence here is very helpful and calming for sure,” said Hamilton.

Crews were able to contain the fire at about 9:00 p.m. and will remain at the scene overnight to monitor for hot spots.

Fire officials say the building was completely destroyed and neighboring apartment buildings sustained significant damage.

“The building on the west side, we had to go inside and have an interior attack to put out the fire inside the building and as well as the building on the east side as well,” said Harley Spate, CFD Battalion Chief.

One person was treated for smoke inhalation and so far no other injuries have been reported.

About two dozen people will not be allowed to return home and officials say it will be some time before repairs can be made.

“There’s damage on both sides of the building. We had one dog pulled out of one of the structures. We have about two dozen residents that are going to have to be rehoused and right now CEMA is looking after that,” said Spate.

Fire investigators are at the scene and are working to determine the origin and cause of the fire.

Anyone who was in the area and has any information, photos or video of the fire especially prior to CFD arrival on scene, is being asked to email them to piofire@calgary.ca