During a Dallas air show on Saturday, two vintage military aircraft collided, plummeted to the ground, burst into flames, and sent columns of black smoke into the air. It wasn’t known how many people were in the plane or whether there were any casualties on the ground.

Emergency crews raced to the crash scene at the Dallas Executive Airport, about 10 miles (16 kilometers) from the city’s downtown.

Also read: Watch: Dallas air show aircraft crash

Live TV news footage from the scene showed people setting up orange cones around the crumpled wreckage of the bomber, which was in a grassy area.

“The videos are heartbreaking,” Dallas Mayor Eric Johnson wrote on Twitter, adding that the National Transportation Safety Board had taken control of the crash scene with local police and fire providing support.

The Boeing B-17 Flying Fortress and a Bell P-63 Kingcobra collided and crashed around 1:20 pm, the Federal Aviation Administration said in a statement. The collision occurred during the Commemorative Air Force Wings Over Dallas show.

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What is the Commemorative Air Force Wings Over Dallas airshow?

The Commemorative Air Force, a group established at the Red Bird airstrip and dedicated to the preservation of World War II aircraft, hosts the air show Wings Over Dallas.

The first day of a three-day festival hosted during Veterans Day weekend was supposed to be Saturday; events on Friday were postponed due to bad weather. On the organization’s website, it was noted that activities were also planned for Sunday from 9 am to 5 pm.

Also read: Dallas Mayor Eric Johnson on airshow air crash: Terrible tragedy in our city

A procession of bombers, including the B-17, was to take place on Saturday, followed by fighter escorts, including the P-63.

The CAF was established in 1961 as a nonprofit organisation, and the weekend event was a part of the CAF’s Air Power History Tour, which was promoted as a tour of WWII aircraft around the country. The tour claims that, among other rare aircraft, its performances will feature either or both of FIFI, a Boeing B-29 Superfortress, or Diamond Lil, a B-24 Liberator.