San Francisco, Jul 12 (IANS): BE-4 engine, a key rocket engine of Jeff Bezos' Blue Origin exploded during testing last month, the media reported.

The BE-4 engine, which was due to finish testing in July, and power the company's New Glenn rocket and United Launch Alliance's (ULA) Vulcan Centaur rocket -- detonated about 10 seconds after the firing test on June 30 at a West Texas facility, CNBC reported.

The explosion reportedly "destroyed the engine and heavily damaged the test stand infrastructure".

The company spokesperson confirmed that the engine "ran into an issue while testing Vulcan's Flight Engine 3", the report said.

The company said that there were no casualties and the company is "currently assessing root cause".

"We already have proximate cause and are working on remedial actions," it added.

The engine that failed on June 30 was undergoing an "acceptance test" (ATP), which looks for issues with individual units before flight, ULA President and CEO Tory Bruno said on Twitter on Tuesday.

ULA, who is Blue Origin's customer, was "immediately" made aware of the engine explosion.

"ATP failures are not uncommon. That's why we do them on every single serial number that comes off the line," Bruno added.

Both New Glenn and Vulcan Centaur have been facing some issues.

New Glenn's debut launch was originally targeted for 2020, but delays in the BE-4's development have postponed it repeatedly. No new target date has been set.

The Vulcan Centaur was supposed to debut in early May, but was pushed back after a Centaur upper stage exploded during testing at NASA's Marshall Space Flight Center on March 29. It's unclear when the new rocket will get off the ground.