SKYWAY, Wash. - Three residents were rescued from the third floor of a burning apartment complex early Sunday morning, and one victim was taken to the hospital with life-threatening injuries.

Crews from King County Fire District 20 rushed to the fire at the Greentree Apartments, in the 6900 block of South 123rd Street, after receiving 911 calls from the scene, said Fire District spokesman David Nelson.

When they arrived, firefighters issued a second alarm after finding heavy smoke billowing from a second-floor apartment unit and at least two residents trapped on the third floor.

One resident was rescued with a firetruck ladder, and the other was assisted down the stairs by fire crews, Nelson said.

Meanwhile, firefighters searching other units found a man who had been injured in the fire.

King County Medic One transported him to Harborview Medical Center in Seattle with life-threatening injuries. His condition at the hospital was not released.

The cause of the fire is under investigation by the King County Sheriff's Office. No damage estimate is available at this time, Nelson said.

The Seattle Chapter of the American Red Cross is assisting residents displaced by the blaze.