The Mountain Home Air Force Base in southwestern Idaho was locked down on Sunday, May 17, after an aircraft crash occurred at an air show, authorities said.The incident took place on the second day of the Gunfighters Air Show, a free event that was open to the public and featured the U.S. Air Force Thunderbirds, according to the base. The crash happened about two miles northwest of the Mountain Home Air Force Base, the base said in a statement.At around 12:57 p.m. local time on May 17, the base said an aircraft incident had happened during the air show and emergency responders were at the scene. Earlier, the base said in a statement that it was locked down."An investigation is underway and more details will be released as they become available," the base said in the statement posted on Facebook.At about 1:18 p.m. local time, the Mountain Home Police Department alerted the public that the event had been officially canceled for the remainder of the day. Police advised the public not to travel to or attempt to access the base "as a spectator, as the event will no longer be taking place."The Idaho Statesman reported that rescue crews responded to a midair collision involving a performance involving two E/A-18G “Vikings” Growler demo team aircraft at the air show. During the event, an air show announcer told the crowd that all four Navy pilots were "found safe," according to the newspaper."We had four good parachutes,” an air show announcer said, the Idaho Statesman reported. "The crews were able to eject. They’re located one mile south of where the smoke is. The parachutes came down."USA TODAY has reached out to the Mountain Home Air Force Base for more information.This is a developing story.