Eight people are feared dead after a U.S. Air Force B-52 Stratofortress crashed and burst into flames shortly after takeoff at Edwards Air Force Base in California.

The massive military bomber went down around 11:20 a.m. local time on Monday, June 15, in Southern California, according to military officials.

Base officials said those on board included both military personnel and civilian contractors.

“We lost eight great Americans. This crash is deemed to be unsurvivable,” Col. James Hayes, a deputy commander at the base, told reporters Monday afternoon.

Hayes said the aircraft crashed “immediately after takeoff” and erupted into flames.

The cause of the deadly crash remains unknown. Officials said a full investigation could take about six months.

According to Hayes, the B-52 was on a test mission connected to a radar modernization program when disaster struck.

The names of the victims have not yet been released as officials work to notify their families.

“Our thoughts and prayers are with the families and unit members at this time,” base officials said.

The airfield at Edwards was shut down after the crash, and all inbound aircraft were diverted.

“All non-commercial visitor passes have been suspended until further notice to allow the installation to focus entirely on emergency response operations,” the base said in an update just before 1 p.m. PT.

The Pentagon confirmed the crash but did not provide details on what may have caused it.

“We can confirm a U.S. Air Force B-52 Stratofortress crashed shortly after takeoff on the Edwards airfield at 11:20 a.m.,” Pentagon officials said. “Emergency crews immediately responded to the scene and the situation is ongoing.”

The sprawling Edwards Air Force Base sits about 100 miles north of Los Angeles and stretches across parts of Kern, Los Angeles and San Bernardino counties.

Rep. Vince Fong, a California Republican, asked Americans to pray for the crew and “the entire Edwards community” in a statement posted on X.

His post included a photo showing a large plume of black smoke rising from a field.

The B-52 Stratofortress is one of the most recognizable bombers in the U.S. military. According to the Air Force, the long-range heavy bomber can fly at subsonic speeds at altitudes of up to 50,000 feet.

The aircraft is capable of carrying nuclear weapons as well as precision-guided conventional weapons.

Edwards Air Force Base has long been tied to some of America’s biggest moments in aviation history. The base was established in 1942 on what was then known as Muroc Dry Lake and has grown to more than 300,000 acres.

Retired Air Force Lt. Col. Mike Paoli previously said the base operates almost like its own town, with more than 11,000 residents, including military personnel and civilians.

The last major crash at the base happened on May 18, 1992, when a twin-engine Mitsubishi MU-2 Marquise crashed during landing. Two crew members were killed, and seven passengers were seriously injured.

Officials said more information about Monday’s crash will be released as the investigation continues.