LYNNWOOD, Wash. - Two firefighters suffered non-life threatening injuries after battling a 3-alarm fire at a Lynnwood apartment building Wednesday night.

Fire crews remained at the scene Thursday morning putting out hot spots after the massive fire destroyed an unoccupied senior apartment building that was under construction in the 19800 block of Scriber Lake Road.

An apartment complex adjacent to the unoccupied building suffered heat damage from the fire, and around 150 residents were evacuated. Officials said Thursday morning that all 36 units in the complex are presently unlivable due to heat and water damage.

The fire was reported just before 9:30 p.m. At one point, the flames were so intense, fire crews evacuated residents in the apartment complex next door.

Julie Moore, spokesperson for the Lynnwood Fire Department, the fire was under control late Wednesday night, but crews were still "defensive battling" the remains of the fire.

"The structure is collapsing in on itself," said Moore. "The surrounding buildings seems to be OK for now."

The firefighters were transported to Swedish Edmonds hospital for treatment.

The Red Cross were providing shelter to the evacuated residents.

The cause of the fire is not yet known, according to Moore, and will be determined by the fire marshal.

Photos: 3-alarm fire in Lynnwood