ATLANTA (AP) -- A company spokesman says a Delta plane headed to Philadelphia had to return to the gate just before takeoff from Atlanta because of an engine fire.

Delta spokesman Carlos Santos said the plane was taxiing along the runway Saturday afternoon when there were reports of "some flames coming out of the engine." He said airport fire trucks responded immediately.

It was not immediately clear what caused the fire.

Santos said there wasn't any smoke in the cabin and passengers were quickly evacuated from the plane. He said all passengers would be put on flights to Philadelphia later Saturday.