SEATTLE - A fire was reported on an American Airlines airplane that was set to depart from the Seattle-Tacoma International Airport, but was quickly extinguished.

No injuries were reported from the incident Wednesday morning.

SeaTac airport spokesman Brian DeRoy says the Airbus 320 was scheduled to depart to Philadelphia at 8:10 a.m. when the fire broke out.

DeRoy says the plane was on the taxiway going toward the runway when smoke started coming out of the back of the plane. He says a spark in the auxiliary power unit just below the tail section started a small fire.

The Port of Seattle Fire Department responded and put the fire out. The aircraft headed back to the gate.

There was no immediate information on what caused the fire.

American Airlines released the following statement after the fire:

“Prior to departure from Seattle, American Airlines flight 728 experienced a mechanical issue with the auxiliary power unit (APU). The Port of Seattle Fire Department responded after flames were reported from the APU exhaust. Once the aircraft was cleared, the Airbus A320 taxied back to the gate. Our maintenance team is currently inspecting the APU. We apologize to our passengers for the inconvenience.”