Orange County firefighters wash down a fellow firefighter wearing a hazardous material suit after the firefighter came out of a building on Challenger Tech Court in the Research Park where an unknown acid was spilled on Tuesday, December 14, 2004. A small fire started inside the building, activating a sprinkler system, according to Orange County Fire Rescue spokesman Bill Murphy. Water from the sprinkler mixed with an acid, causing a reaction, and someone inside the building reported hearing an explosion, Murphy said. Firefighters dressed in hazardous material suits entered the building and reported that the acid appeared stable. The building contained aplating company, Murphy said. About 30 firefighters responded to the incident.