Thursday's fire at the Coach House apartment complex on Boston Road was caused by a heat gun according to Chelmsford Fire Department captain Hank Houle.

The gun was being used by a resident to unfreeze pipes, but the resident accidentally was not paying attention momentarily, leaving the gun in one location for too long on the pipes, creating sparks that ignited wood located behind a nearby wall.

Firefighters needed to remove the wall and portions of the apartment's balcony in order to fight the blaze, which according to accounts obtained by other residents was mainly smoke.

No injuries were reported in the incident and property damage was minimal.