Eight Americans are dead after a U.S. Air Force B-52 bomber aircraft crashed shortly after taking off for a routine test mission on Monday from Edwards Air Force Base in California.

Col. James Hayes, deputy commander of the 412th Test Wing at Edwards Air Force Base, said in a press conference later Monday that the plane “took off, and immediately after takeoff, crashed and burst into flames … It was deemed that this was an unrecoverable crash and unsurvivable.”

The victims include a “mixed crew of military, government civilians, and government contractors,” Hayes said.

First responders were deployed immediately after the crash and are still working the scene.

The notification process for the victims’ families is currently underway, Hayes said. Their identities will be released 24 hours after the next of kin notification takes place.

“​​Our thoughts and prayers are with the families of those that lost their loved ones,” Hayes said. “This is a tragedy, and this is going to be the worst days of their lives. We understand that, and we want to keep them in our thoughts and prayers.”

The crash remains under investigation, and the colonel said there is no indication yet as to what might have caused the tragedy. Even if there was, he said he wouldn’t be able to release that information so soon.

Providing the cause of the crash to the public entails a process that could take up to six months, Hayes said.

Rep. Vince Fong (R-Calif.) in a post on X: “Please join me in praying for the B-52 crew at Edwards Air Force Base and the entire Edwards community.”

Video footage of the incident showed the smoldering wreckage of the plane at the base, which is located in both Kern and San Bernardino counties.

The B-52 Stratofortress is a long-range bomber that was introduced in the 1950s as a central part of U.S. air power. The planes are capable of carrying conventional and nuclear weapons, and they have been used in a range of U.S. military confrontations, most recently in the war with Iran.

The bomber usually has a crew of five, including a commander, pilot, radar navigator, navigator, and electronic warfare officer. It also can carry a payload of up to 70,000 pounds and has a range of 8,800 miles, the Air Force says.

The Air Force says it is expecting to operate B-52s until the year 2050.

Both the Air Force and NASA carry out test flights of new and experimental aircraft at the air base, which is located in the Mojave Desert, according to its website. Earlier this month, NASA’s X-59 experimental aircraft flew faster than the speed of sound in a milestone event at Edwards Air Force Base, the space agency said.

The crash is one of several involving the U.S. military that have occurred in the past few weeks.

On May 17, two Navy EA-18G Growlers collided with one another in midair in an air show at Mountain Home Air Force Base in Idaho, the military said.

Over the past weekend, a military plane crashed near Mount Rainier in Washington state during a training flight, local officials said.

Before the crash on Monday, the most recent fatal incident involving a B-52 occurred in 2008, when six Air Force members died when a bomber crashed into the Pacific Ocean after taking off from a base in Guam. The plane was due to take part in a parade flyover.