Investigators say an early morning fire that destroyed one Salt Lake apartment and damaged two others early Sunday is "suspicious."

Firefighters were called to a four-plex at 855 S. 1500 West at 2:51 a.m. and found flames shooting out of one of the units.Capt. Devin Villa said the apartment was vacant at the time, and the occupants of the other units escaped without injury. Twenty-one firefighters had the blaze under control by 3:08 a.m., confining the fire damage to one unit.

Two other units sustained minor smoke damage, but residents were allowed to re-enter their homes by 4 a.m. Villa estimated the damage to the four-plex at $50,000. Arson investigators sifted through the rubble in the burned apartment on Sunday searching for the cause of the fire.