Crew members of two U.S. Navy planes ejected after their jets collided in midair on Sunday afternoon during an air show at the Mountain Home Air Force Base in Idaho, according to the base.

The episode happened shortly after noon local time when the jets, EA-18G Growlers, collided during a demonstration.

The jets had a total of four crew members aboard, all of whom successfully ejected, according to the base, which added that they were being medically evaluated.

A video on social media showed the jets spinning toward the ground. The four crew members deployed their parachutes and ejected from the planes, which then exploded into balls of fire.

“They crashed in an unpopulated area off base,” said a witness, Lindsay Dressler. She said a brush fire broke out after the crash.

The “aircraft incident” took place two miles northwest of the base, the Mountain Home Air Force Base Gunfighters said on Facebook. The base is home to the U.S. Air Force’s 366th Fighter Wing, also known as the Gunfighters.

The base, in southwestern Idaho about 50 miles south of Boise, the state capital, was locked down on Sunday afternoon.

A spokesman for the Federal Aviation Administration referred inquiries to the Mountain Home Air Force Base.

The planes in the collision were EA-18G Growler Airborne Electronic Attack Aircraft, according to the base and the Navy. The planes were assigned to the show from Whidbey Island, Wash.

The EA-18G Growler is part of the Navy’s “first line of defense in hostile environments,” according to its website. It is used by the VAQ-130 squadron, the oldest electronic warfare squadron in the Navy, known as the Zappers.

In April, the 366th Fighter Wing at the Idaho base announced the Gunfighter Skies Air Show, which began on Saturday and was scheduled to run through Sunday.

The free, public event featured the U.S. Air Force Thunderbirds, the Mountain Home Air Force Base said in a news release.

“Gunfighter Skies will showcase the precision, capability and readiness of the U.S. Air Force,” the base said.

The base is home to about 8,600 people, including service members and their families.

Mountain Home Police said the show was canceled and urged people to avoid the area around the base.

Robert Robinson, 26, was driving to the event with his wife when the crash happened.

“All of a sudden, we saw the full profile of one of the planes,” he said. “I was like, that’s either a cool stunt or something major just happened.”

He said it took him several minutes to realize it was a collision.

“I saw the major change in flight direction, and you know, control of the aircraft being lost, and that was about the moment that I realized, oh, something was very wrong. It was surreal to say the least,” he said.