State police fire marshals are being called upon to determine the cause of a Friday fire in Butler that destroyed a recovery house for substance users and resulted in one firefighter being treated at a hospital for heat exhaustion and several others being evaluated at the scene.

Butler Fire Chief Chris Switala said the fire started in the area where three garages were located behind the recovery house at 332 Broad Street, which was destroyed in the fire, but fire marshals will investigate to determine the cause of the fire.

Eight people had been living in the recovery house, he said.

The fire melted the siding on the house next door, at the corner of Broad and West Penn streets, and scorched the exterior of the house next to it on West Penn Street, Switala said.

The detached garages of the recovery house and the house at the corner were destroyed and the garage of the house on West Penn Street was damaged, he said.

A firefighter from the Butler Township Volunteer Fire District was taken to Butler Memorial Hospital with heat exhaustion, treated and released, Switala said. Several other firefighters were evaluated by Butler Ambulance Service medics at the scene due to the heat, he added.

The fire was reported just after 7 p.m. Fire departments from the city, Butler VA, Butler Township, Penn Township, Center Township, Saxonburg and Mars responded.