O'Fallon, MO (KSDK)-   Two people hurt after fire broke out in an O'Fallon Missouri residence overnight have been released from the hospital.

Firefighters responded to the 200 block of Park Ridge Drive around 12:30 Monday morning and found heavy fire and smoke from one side of the two family duplex.

The residents of that portion of the structure; described as a husband and wife, were both injured and transported to an area hospital.

Two residents in the adjoining unit were alerted to the blaze by a neighbor, and they got out safely.

Investigators are looking into the possibility the fire originated on an outside deck of the building. The two victims were released from the hospital Monday afternoon.