LINCOLN, Neb. (AP) — A Lincoln fire investigator says a bathroom light overheated and ignited a fire inside a vacant downtown building.

The fire occurred before 8 a.m. Tuesday.

Investigator Damon Robbins says a trespasser inside the building likely left the ceiling light on in the bathroom on the northwest side of the building.

The fire burned through the walls of one of the rooms inside, but was under control shortly within an hour. No one was in the building at the time of the fire, but two firefighters suffered minor injuries in bringing the fire under control.

A fire investigator is working to determine how much damage was done to the building owned by New Generation Investments LLC.