Wellston, MO (KSDK)-   A firefighter was slightly injured overnight while in the line of duty.

Officials with the Mid County Fire Protection District did not immediately identify the injured firefighter who suffered a shoulder problem while battling a pair of house fired early Monday morning.

The first fire was at a structure in the 6400 block of Ridge Avenue.  It's believed the first fire is where the firefighter initially hurt himself.

Not long after the first call, the firefighter was at a second fire scene at a home in the 6200 block of Lenox where the firefighter gave him further discomfort and he was transported to a local hospital.

Authorities say the fireman was treated and released a short time later.

While there was no immediate indication the two fires were suspicious, the St. Louis County Bomb and Arson investigators were called to seek a cause for the fires.