ATLANTA (AP) — A tire explosion in a Delta Air Lines maintenance hangar near Atlanta airport killed two workers and seriously injured another on Tuesday.

Delta said the explosion occurred while wheel components were being disassembled for maintenance at a wheel and brake shop. The parts were not attached to an aircraft at the time, the airline said.

The U.S. Occupational Safety and Health Administration said it had launched an investigation. Delta said it was cooperating with authorities but the cause of the explosion was not yet known.

Several fire departments and Atlanta police responded to the maintenance hangar near Hartsfield-Jackson Atlanta International Airport shortly after 5 a.m., the Atlanta Journal-Constitution reported. The airport said air traffic was not affected, and Delta said maintenance operations were not impacted.

“The Delta family is heartbroken over the loss of two team members and the injury of another following an incident this morning at the Atlanta Technical Operations Maintenance facility,” Delta said in a statement. “We have pledged our full support to family members and colleagues during this incredibly difficult time.”

Delta thanked first responders and medical teams and said the injured worker remained under medical care late Tuesday afternoon.

“We are now working with local authorities and conducting a full investigation to determine what happened,” the Atlanta-based airline said.

The Federal Aviation Administration said it was in contact with Delta but had referred a request for more information about the suspected accident to the airline. Eric Lucero, a spokesman for OSHA, said the federal Occupational Safety and Health Administration has launched an investigation.

The facility where the explosion occurred is part of Delta TechOps, which performs maintenance, repair and overhaul for Delta and more than 150 aviation and airline customers around the world.