LOS ANGELES, Jan. 20 (Xinhua) -- Two U.S. Army pilots were killed in a helicopter crash in the California desert Saturday morning during a routine training exercise, the Fox news channel reported.

Both the pilot and the co-pilot were killed and the cause "is currently under investigation," Lt. Col. Jason S. Brown, an Army spokesman at the Pentagon, was quoted as saying.

The crashed AH-64 Apache gunship was attached to the Army's 4th Infantry Division based out of Fort Carson, Colorado, the report said.

It was flying to the National Training Center at Fort Irwin in California, 240 km northeast of Los Angeles, for a regular training rotation.

The fatal accident occurred hours after the U.S. government shutdown and it marked the first known deadly crash for the U.S. military in 2018.

As many as 37 U.S. troops were lost in crashes of military non-combat planes flying routine operations till November in 2017, according to an investigation report of Fox.

It is more than 130 percent higher than the number of those killed in non-combat plane crashes at this point in 2016.

In November, the head of Army aviation, Maj. Gen. William Gayler, told Congress that his pilots' flight hours were at their lowest levels in 30 years after years of budget cuts.