Firefighters battled a blaze at a defense contractor's workshop Thursday night in Norcross.

Eleven firefighters were exposed to an acid-based chemical used in the process of corrosion protection for aluminum, said Gwinnett fire department spokesman Lt. Thomas Rutledge. The firefighters' uniforms were decontaminated as a precautionary measure.

No EMS Technologies employees were in the annex at the time of the fire, said Anne Wainscott-Sargent, a company spokeswoman. The building sustained substantial smoke and water damage, but no one was injured, she said.

The facility, located in Technology Park Atlanta office park at 660 Engineering Drive, is part of EMS's Defense and Space Systems Division, which makes defense electronics. The fire started in the part of the building that houses the metal-finishing processes, where the metal hardware is treated for corrosion resistance, Wainscott-Sargent said. The company expects the damaged part of the facility to resume operation by the end of next week. Production would not be affected by the fire, she said.