(NewsNation) — Two World War II-era military airplanes collided at the Wings Over Dallas Airshow in Texas Saturday, according to the Federal Aviation Administration.

Officials said a Boeing B-17 Flying Fortress and a Bell P-63 Kingcobra crashed near the Dallas Executive Airport at around 1:20 p.m. local time.

Several videos posted on Twitter showed two aircraft appearing to collide in the air before they both rapidly descended, causing a large fire and plumes of black smoke to billow into the sky.

Dallas Mayor Eric Johnson tweeted Saturday afternoon that the number of casualties has not yet been confirmed, but no spectators or others on the ground were reported injured.

“The videos are heartbreaking,” he wrote. “Please, say a prayer for the souls who took to the sky to entertain and educate our families today.”

According to The Dallas Morning News, the Dallas Fire-Rescue Department active incidents list showed dozens of units responding to an “Alert 3″ — code for an aircraft crash or a fire involving an aircraft.

According to WFAA-TV, debris from the collision could be seen on a nearby highway.

The FAA and the National Transportation Safety Board have launched investigations, and additional updates are expected.

In a statement, the FAA said it will release the aircraft registration numbers at the scene after investigators verify them. You can look them up on this webpage.

Neither the FAA nor the National Transportation Safety Board identifies people involved in aircraft accidents, the statement said.

The Associated Press contributed to this report.

Check back as this story is developing.