Massive Riverdale house fire under investigation

RIVERDALE, Ill. (WLS) -- Investigators are trying to determine what sparked a large house fire in south suburban Riverdale.

Firefighters arrived at the scene in the 0-100-block of East 138th Street early Friday morning to find heavy smoke and large flames shooting from the upstairs windows and roof of the two-story home.

The house is occupied, but it's unclear if anyone was inside when the fire started.

The cause of the fire is under investigation.