The explosion took place at the airport’s maintenance area early Tuesday, killing a Delta employee and a contractor while leaving another airline worker badly injured, according to local outlet WSB2.

Delta expressed its condolences to the victims in a statement issued Tuesday.

“The Delta family is heartbroken at the loss of two team members and the injury of another following an incident this morning at the Atlanta Technical Operations Maintenance facility (TOC 3). We have extended our full support to family members and colleagues during this incredibly difficult time,” the airline wrote.

“The Delta family is grateful for the quick action of first responders and medical teams on site. We are now working with local authorities and conducting a full investigation to determine what happened.”

The plane traveled from Las Vegas to Atlanta on Sunday night. It was not immediately clear what caused the explosion.