Texas ? The Air Force grounded all T-38C training jets on Thursday, following the second fatal crash involving the aircraft in eight days, the military said.

Two pilots died when their high-altitude, supersonic plane went down during a routine training mission, according a statement from Sheppard Air Force Base in Wichita Falls, Texas.

The two-seat plane was assigned to the 80th Flying Training Wing, a multinational organization that produces future combat pilots for NATO. The names of the airmen were not immediately released.

The crash follows the deaths of two pilots whose training jet crashed April 23 at Columbus Air Force Base in Mississippi.

“At this point we have no indication that there was any tie between the two,” said Capt. John Severns, Chief of Media Relations for Air Education Training Command at Randolph Air Force Base near San Antonio.