( KTRS ) Authorities in southwestern Illinois are investigating the cause of a fire that left two people dead.

Police in Highland say two 911 calls alerted fire officials and police to smoke coming from a house around 8 a.m. Sunday. Authorities say the house was fully engulfed in flames when police, paramedics and firefighters responded. The two people pulled from the residence were already dead.

Highland fire officials say the fire may have started in the basement, but do not know the cause.