One Marine was killed, and another was injured when their helicopter crashed in an unpopulated area in Imperial County on Thursday night, Marine Corps officials announced Friday.

The crash was reported at around 7:05 p.m. Thursday in the unpopulated area of Imperial Gables, about 180 miles away from the Marine Corps’s air station in Miramar. 

Military officials said an AH-1Z Viper experienced an “aviation mishap” during routine operations before the deadly incident. 

The two pilots inside the helicopter were taken to separate hospitals. One of the pilots was transported to Pioneer Memorial Hospital in Brawley and was declared dead. Another pilot, taken to Desert Regional Medical Center in Palm Springs, was in stable condition, officials said. 

“This Marine made the ultimate sacrifice, and we are forever grateful for his selfless commitment and willingness to go into harm’s way,” Maj. Gen. James B. Wellons, the commanding general of 3rd MAW, said in a statement. “To the family, friends, and loved ones of our fallen Marine, we send our deepest condolences and offer our unwavering support during this time of grief.”

The helicopter was assigned to the Marine Light Attack Helicopter Squadron 369, which is based at Camp Pendleton. It falls under the 3rd Marine Aircraft Wing, which is headquartered at MCAS Miramar.

The Marine Corps said it will not release the identity of the deceased service member until 24 hours after all next of kin notifications have been completed.