Two Army grounds maintenance contractors were medevaced by helicopter Monday after they received "severe" injuries from unexploded ordnance that detonated at Makua Military Reservation, officials said.

"I did find out from our personnel there that arrived on scene, they were civilian contractors. One was operating a grass trimmer when he made contact with the unexploded ordnance," said Honolulu Fire Department spokesman Capt. David Jenkins.

Jenkins described the grass trimmer as hand-held. Another worker nearby also was injured when the explosive detonated, Jenkins said.

He described the injuries as "severe."

"Of course, the person closer had more injury," Jenkins said, "and the (other person) was a little bit farther away and his injuries were less. I can’t really go into the actual details, but they were both severe."

The incident was reported at 1:45 p.m., and a contracted medevac helicopter used by the Army was used to transport the individuals to Queen’s Medical Center, officials said.