Chemicals mixed at a plating facility in Fridley set off a small explosion Tuesday that burned three employees and prompted the building's brief evacuation, authorities said.

The "flash explosion" occurred shortly after 11 a.m. at Incertec Plating on 83rd Avenue NE., just west of University Avenue, police said.

The three employees, all men, were splashed with acid. They were rinsed by firefighters at the scene, then taken to a hospital, where they were treated for their injuries and released, the company said.

Fire Chief John Berg said it was not known what caused the chemicals to explode. He identified them as phosphoric and nitric acid.

Minnesota OSHA was notified and will investigate.

Authorities were alerted to the explosion at 11:07 a.m., and after arriving, firefighters went through the plant to ensure it was free of hazardous vapors. The building reopened shortly after 12:30 p.m.

Two of the injured men were taken to Mercy Hospital in Coon Rapids. The third was taken to Hennepin County Medical Center with burns to the face.

Rob Clark, Incertec's director of operations, said about 75 employees were removed from the facility as a precaution.

Clark, who received reports from Fridley while at the company's facility in Kansas, said that Incertec, founded in Fridley 18 years ago, had a "very good" safety record. "We haven't had any significant issues whatsoever," he said.

Minnesota OSHA said the company had not been the subject of a safety investigation for at least 10 years. But it was cited and fined twice in June 2009 for a "serious" violation for misusing PVC pipe and for a "nonserious" violation for a damaged electrical conduit. The fines totaled $800.

A mid-1990s fire claimed the company's original Fridley facility, Berg said.

Incertec does custom plating for metals and plastics. Its clients have included Goodrich Aerospace, Lockheed Martin, Honeywell and Medtronic.

Anthony Lonetree • 612-673-4109 Paul Walsh • 612-673-4482