A C-130 crashed Sunday in southwest South Dakota while battling fires in the Rocky Mountain region, U.S. Northern Command (NORTHCOM) said in a statement.

The military cargo plane equipped with the Modular Airborne Fire Fighting System (MAFFS) crashed around 8:30 p.m. EST while fighting the “White Draw Fire” near Edgemond, S.D. The C-130 belonged to the North Carolina Air National Guard based at Charlotte-Douglas International Airport.

NORTHCOM said there were casualties, but did not specify how many or how many were on the plane. NORTHCOM also said the cause of the crash has not been determined and the incident is under investigation.

A NORTHCOM spokesman said seven MAFFS-equipped C-130s are on operational hold at the present time. The 153rd Air Expeditionary Group said in a statement it doesn’t know when MAFFS aircraft will resume operations.

MAFFS is a 40-year old joint effort between the U.S. Forest Service and the Defense Department, according to the 153rd Air Expeditionary Group. MAFFS is designed to provide additional aerial firefighting resources when commercial and private airtankers are no longer able to meet the needs of the Forest Service. The crash is the first in the history of MAFFS, NORTHCOM said.

MAFFS is a self-contained aerial firefighting system owned by the Forest Service that can discharge 3,000 gallons of water or fire retardant in less than five seconds, covering an area one-quarter of a mile long by 100 feet wide. Once the load is discharged, it can be refilled in less than 12 minutes, according to NORTHCOM.

C-130s are manufactured by Lockheed Martin [LMT].