GRAND RAPIDS, Mich. (AP) -- Authorities in Grand Rapids say a 20-year-old man has been critically injured after falling from a third-story window.

Police say he was attending a party early Saturday morning in an apartment. Witnesses told detectives that he sat on the sill of an open dining-room window, leaned back and fell onto a concrete slab.

Investigators say he was taken to a nearby hospital with life-threatening injuries. They also say alcohol was a factor in the accident.

Police say he has been identified but aren't releasing his name.