An explosion Saturday morning at a West Caldwell meat processing plant sent two contractors to the hospital with serious burns and forced an evacuation of the smoke-filled building.

West Caldwell Fire Chief Jim Alvine said two contractors were working on an electrical panel at Al & John Inc. on Clinton Road when it exploded, sparking a fire in the electrical room on the building's right side and filling the entire rear of the building with smoke.

Contractors Francois MacFarlane, of Brooklyn, N.Y., and Jason Defaoite, of Oak Ridge, N.J., were treated at the scene and transported to St. Barnabas Medical Center in Livingston with serious burns, West Caldwell police chief Michael Bramhall said. Their injuries are believed to be the result of an arc flash in the electrical room.

The West Caldwell Fire Department had the situation under control in about 15 minutes, Alvine said. The electrically charged nature of the fire made it unsafe for firefighters to extinguish with water, but a shutdown of the electrical panels caused the fire to dissipate and eventually extinguish on its own.

Once extinguished, firefighters performed a search of the building and removed the thick smoke that clouded its interior.

As of 11:30 a.m. Saturday, Alvine said the power at the plant had been restored in all but the right side of the building where the explosion occurred. The Occupational Safety and Health Administration conducted a complete investigation later in the day.

The Caldwell Fire Department, West Essex First Aid Squad, MONOC Paramedics, West Caldwell Police Department and Fairfield Police Department also responded and assisted at the scene.