Emergency crews in Fort McMurray spent much of Friday afternoon on the scene of a massive blaze that destroyed a condominium complex under construction.

Firefighters were called to the Siltstone Place, a four storey condominium building under construction, at about 12:30 p.m.

Officials said all of the contractors and workers onsite had evacuated, and flames were showing when firefighters arrived.

“We went into defensive mode,” Assistant Deputy Fire Chief Jody Butz said. “[We] surrounded it and started throwing water at it.”

By mid-afternoon, fire crews from Regional Emergency Services from Fort McMurray, and members of the Saprae Creek Volunteer Fire Department were on the scene, along with crews from Syncrude and Suncor, who were helping support firefighters.

A large section of the structure collapsed as firefighters tried to gain the upper hand on the blaze.

“The building is unsafe for our guys to go in there and uproot some of these hot spots,” Butz said. “So we’re going to have to attack it from the outside in.”

Another apartment complex near the one engulfed in flames was saved by crews, but Siltstone Place is a total loss, destroying between 75 and 80 units.

It’s not clear what caused the fire.

Calls to the owners of the development, Integrated Management and Realty Limited were not returned.

With files from Veronica Jubinville