U.S. federal investigators are looking into what caused a former Soviet warplane to suddenly drop out of the sky and crash at a Florida air show Saturday.

Officials say the pilot was killed instantly when the Yak-52 plane fell out of a formation with other jets and plummeted to the ground.

It crashed less than a kilometer from where thousands of people were enjoying the Wings Over Flagler show, north of Daytona Beach.

The Aerostar Yak-52 plane was built in 1983.