The cause of the May 21 fire in Butler that destroyed a recovery home on Broad Street, destroyed or damaged neighboring structures, and left a firefighter with heat exhaustion could not be determined, and will be listed as undetermined.

Butler Fire Chief Chris Switala said Tuesday that state fire marshals determined the fire started at the rear of the recovery house at 332 Broad St. and its detached garage, but were not able to pinpoint the cause of the fire.

Switala said a fire marshal completed the site examination Monday. Unless additional information comes to light, the cause will be listed as undetermined, he said.

The fire started just after 7 p.m. It caused exterior damage to two neighboring houses, which had detached garages. One of the garages was destroyed and the other was damaged.

A Butler Township Volunteer Fire District firefighter was treated at Butler Memorial Hospital for heat exhaustion, and several other firefighters were evaluated at the scene. Seven fire departments responded to the fire.