``There was a brand-new boiler, and they were trying light it, get it to work, and they had an explosion. It blew the front and back off the boiler,'' said Randy Sanders, assistant chief for the Campbell County Fire Department.
Mark A. Haratyk, 25, of Gillette, died of massive head injuries Monday, Campbell County Coroner Tom Eekhoff said.
Haratyk, who was an employee of Viking Explosives, was pronounced dead at the scene.
Authorities did not immediately release the names of the two injured.
The Office of Safety and Health Administration is investigating.
The explosion happened shortly after 10 a.m. Monday, according to reports by Campbell County sheriff's and fire department officials.
Sanders said there was no fire involved in the explosion.
The incident didn't appear to involve any of the explosive materials manufactured at the site. Sanders said the boiler was contained in a small building that housed only the boiler itself.
Viking Explosives is one of four companies that either manufacture, mix or deliver explosive materials to coal mines in the area.