A US military helicopter crashed in Fort Hood, Texas, on Monday, killing all four crew members, US Army officials said.
The UH-60 Blackhawk helicopter crashed Monday evening in the northeast portion of the sprawling Texas military base.
A statement from the base said the crew was assigned to Division West, First Army, and were on a routine training mission at the time of the crash.
Officials said they had not determined the cause of the crash and an investigation is under way.
Meanwhile, a US Army helicopter crashed in South Korea on Monday night, claiming the lives of two pilots during their routine training mission.
The AH-64 Apache helicopter went down on a road in Wonju, 50 miles east of the US Camp Humphrey's base, US Army said.
"We offer our heartfelt prayers and condolences to the families of the Soldiers involved in this tragic incident,” said Lt. Col. Mark Gillespie, the deputy commander of 2nd Combat Aviation Brigade in a statement. “Our first priority is to provide their families with the support they need during this difficult time."
This year, there have been a number of accidents involving US military aircraft.
In September, a Marine was killed and 11 others injured when a military helicopter made a hard landing at Camp Lejeune in North Carolina.
Also in the same month, two soldiers were injured in a different hard landing incident near Denver, Colo. No fatalities were reported in that incident.
In August, Reuters reported that a US military helicopter crashed in waters off the Japanese southern island of Okinawa during a training mission injuring seven people. The accident promoted Japan's government to demand a probe and steps to prevent a recurrence.
In March, a UH-60 Black Hawk helicopter plunged into the Santa Rosa Sound along the Florida Panhandle during a training exercise in foggy conditions killing seven Marines and four soldiers on board.
In June, The Christian Science Monitor compiled a rundown of military aircraft accidents in the first half of 2015:
- On Jan. 20, a California National Guard Black Hawk helicopter was forced to land on its side in an emergency landing at Ramona Airport in Ramona, Calif., during a training mission. The pilots were able to escape on their own with minor injuries.
- On Feb. 22, a Marine fighter jet crashed near Statenville, Ga., while conducting low-altitude training exercises. The two crew members were able to eject from the plane and walked away with no serious injuries.
- On March 10, a Black Hawk helicopter crashed off the coast of Florida killing seven Marines and four soldiers. Recovery efforts were stalled during the search because of heavy fog and weather conditions.
- On May 17, a Marine aircraft crashed at Bellows Air Force Station in Waimanalo, Hawaii, killing two crew members on board and injuring more than a dozen others.
- On May 22, an aircraft landing at Naval Air Station North Island crashed into San Diego Bay in southern California, but the pilot was able to eject and was rescued by a civilian boat.