(CHARLOTTE) -- The military says Four airmen died and two others were seriously injured when a Modular Airborne Fire Fighting System (MAFFS) equipped C-130 belonging to the 145th Airlift Wing, North Carolina Air National Guard, crashed Sunday while fighting a woodland fire in Southwestern South Dakota.

Dead are Lt. Col. Paul K. Mikeal, 42, of Mooresville, N.C.; Maj. Joseph M. McCormick, 36, of Belmont, N.C.; Maj. Ryan S. David (pronounced da-veed), 35, of Boone, N.C.; Senior Master Sgt. Robert S. Cannon, 50, of Charlotte.

"Words can't express how much we feel the loss of these Airmen," said Brig. Gen. Tony McMillan, 145 AW Commander.  "Our prayers are with their families, as well as our injured brothers as they recover."

Mikeal was assigned to the 156th Airlift Squadron as an evaluator pilot and had more than 20 years of service.  He leaves behind a wife and two children.

McCormick was an instructor pilot and chief of training for the 156th Airlift Squadron.  He was married with four children.

David was an experienced navigator and was also assigned to the 156th. He joined the North Carolina Air National Guard in 2011 after prior service in the active-duty U.S. Air Force.  He is survived by his wife and one child.

Cannon had more than 29 years with the Charlotte unit and was a flight engineer with the 145th Operations Support Flight.  He was married with two children.

The plane was carrying a crew of six, two men survived but remain hospitalized and with serious injuries. The names of the injured will not be released.

The crew and its aircraft along with two other 145th C-130s and three dozen airmen flew from Charlotte to Peterson Air Force Base in Colorado Springs, Colo., Saturday to assist with fighting forest fires in the Rocky Mountain region.  They were due to move to a base in Cheyenne, Wyo., on Monday.

"The support of civil authorities during natural disasters is a key and unique mission of the National Guard," said Army Maj. Gen. Gregory Lusk, the adjutant general of North Carolina National Guard "The MAFFS mission is probably one of the seminal missions of the Air National Guard, representing interagency coordination between the Guard and the U.S. Forest Service, the Department of Homeland Security, and Department of Defense organizations to suppress the fires."

The crash occurred around 6:30 p.m. mountain time near Edgemont, S.D., as the crew assisted with battling what is being called the White Draw fire. The cause of the crash is unknown and is under investigation.