Authorities say they still don't know what caused a small explosion at a northeast Iowa factory that injured three workers.
Postville Fire Chief Jeffrey Bohr says the explosion early Monday at the Norplex-Micarta composite laminates plant in Postville has been deemed accidental. Officials say employees were cleaning equipment at the time.
Bohr says firefighters and the factory's sprinkler system helped contain fires caused by the explosion. Officials also shut down natural gas valves to prevent further explosions.
Three workers were injured, including one who was airlifted to a burn unit in Iowa City. The employee's condition is unclear, though Bohr says the employee is improving.
Another worker was treated and released from an area hospital, and the other declined treatment at the scene. Their names have not been released.