Debris was scattered across Dallas Executive Airport after the crash. (AP)

Two World War II-era planes collided Saturday at an air show in Dallas, according to US police, with social media footage showing the planes colliding and exploding on the ground.

The number of persons aboard the two planes, a Boeing B-17 Flying Fortress and a smaller Bell P-63 Kingcobra, was not immediately known, according to the Federal Aviation Administration.

It was also unclear whether anyone survived the early afternoon accident at Dallas Executive Airport, which occurred during the Wings Over Dallas airshow.

⚠️ GRAPHIC VIDEO: A mid-air collision involving two planes near the Dallas Executive Airport, today. The accident took place during the Wings Over Dallas WWII Airshow at 1:25 p.m., according to Dallas Fire-Rescue. A @FOX4 viewer took this video. @FOX4 is working for more details. pic.twitter.com/jdA6Cpb9Ot
— David Sentendrey (@DavidSFOX4) November 12, 2022

While the number of casualties was not immediately known, Dallas Mayor Eric Johnson stated that "no spectators or others on the ground were reported harmed."

Several videos uploaded on social media showed the smaller plane descending toward the lower-flying B-17 and colliding with it.

The planes appeared to break up into several large pieces after the collision before crashing into the ground and exploding in a ball of fire, creating a massive plume of black smoke.

The FAA and the National Transportation Safety Board said they would investigate the incident.

On October 2, 2019, seven persons were killed in an accident at an airfield in Windsor Locks, Connecticut, in one of the last significant B-17 crashes.