Two men were hurt and a piece of construction machinery destroyed Tuesday after an explosion at a salvage company in Campbell Industrial Park.

The blast happened shortly after 3 p.m. and started a fire that burned about 10,000 square feet of scrap material at Leeward Auto Wreckers, said Hono­lulu fire Capt. Terry Seelig.

Five engine and two ladder companies found smoke and flames rising from a pile of auto parts and other scrap material on the junkyard’s property at 91-209 Kuhela St.

Firefighters dumped more than 30,000 gallons of water on the flames in 20 minutes and also used compressed foam. They brought the two-alarm blaze under control within 45 minutes.

Paramedics took a 36-year-old man in serious condition to the burn unit at Straub Clinic & Hospital, authorities said. A second man was treated and released at the scene.

"This is one of those freak accidents where they were handling material," said Leeward Auto Wreckers manager Albert Ter­nora Jr.

He said a supervisor was moving around scrap material with an excavator when something exploded in the machinery’s claw. The man apparently had burns to his arms and was able to get out of the cab and douse himself with water. Another employee was blown back by the explosion and scraped his knee.

A fire investigator determined the explosion was caused by a cylinder of acetylene — a highly flammable fuel often used for welding torches — after finding remnants believed to be from an acetylene container and because the company recently received a shipment containing such cylinders, Seelig said. The investigator determined the fire destroyed the excavator, causing about $300,000 in damage.