An investigation is under way after an incident on Sunday at an air show at Mountain Home air force base in western Idaho, a spokesperson told Reuters.

A social media post by Airshow News said that two EA-18G Growler jets crashed 2 miles from Mountain Home air force base during the Gunfighter Skies air show. Following the midair collision, four parachutes were seen deployed, Airshow News said.

“Emergency responders are on the scene and investigation is underway and more details will be released as they become available,” a Mountain Home spokesperson told Reuters.

The Mountain Home air force base said in a social media post that it was locked down following the unspecified incident during the gunfighter skies air show. Responders were on the scene and an investigation was under way.

Multiple witnesses reported two planes crashed and videos posted online showed four parachutes opening in the sky as the planes plummeted to the ground.

No other information was immediately available, said a person who answered the phone at the 366th fighter wing public affairs office.

The Mountain Home police department issued a notice that the air show was canceled and cautioned not to travel to the area.

Organizers say the popular air show that includes flying demonstrations is a celebration of aviation history and a look at modern air force capabilities.

The air show’s official site lists the E/A-18G “Vikings” Growler demo team as one of the scheduled performers.