Two United States (US) Navy EA-18G Growler jets collided mid-air while performing an aerial demonstration during the Gunfighter Skies air show at Mountain Home Air Force Base in Idaho on Sunday.

All four crew members aboard the two jets ejected safely following the collision, a US Navy spokesperson told the international media outlet.

The incident took place roughly two miles northwest of the base during the second and final day of the event. A fire broke out after the collision and the base was briefly locked down, with the remainder of the air show cancelled.

“The aircrew involved in the incident are in stable condition,” Mountain Home Air Force Base said in a statement posted on social media. The base added that crew members were being assessed by medical personnel.

“Thank you to all our guests for your patience and compassion, which has allowed us to quickly and safely respond to the incident,” the statement read.

The two Growlers were assigned to an electronic attack squadron based in Washington state. The US Navy puts the cost of each aircraft at around $67 million, putting the total loss at roughly $134 million.

Kim Sykes of Silver Wings of Idaho, one of the organisations behind the event, told a local CBS affiliate that no one at the base was hurt. An investigation into the incident is underway.

The Gunfighter Skies air show was previously held in 2018, when a glider pilot died in a separate accident.