O’FALLON, Mo. (KMOX) — An O’Fallon Missouri family escaped serious injures after a fire early Monday.

The blaze broken out around 12:30 a.m. in a duplex in the 200 block of Park Ridge Drive.

When firefighters arrived, the home was completely engulfed in flames.

Officials said a neighbor noticed the duplex was on fire and alerted the family.

Two people were treated at the scene for smoke inhalation.

The cause of the fire is under investigation.