Event Description
The airplane had been pushed from the gate and the #1 engine had been started. During the start sequence of the #2 engine, the flight crew observed a high fuel flow indication. Simultaneously, a passenger seated on the right side of the airplane saw a flame aft of the exhaust. The passenger shouted "fire," opened the #2L door, and deployed the emergency escape slide.
Evacuation
Following the passenger's actions, the remaining passengers began an uncommanded evacuation of the airplane. A flight attendant informed the captain that the remaining passengers wanted to evacuate. The captain then directed that the #1L and #1R doors be opened and the emergency escape slides utilized. The captain secured both engines and entered the cabin.
Aftermath
Upon entering the cabin, the captain stopped the evacuation of the remaining 24 people aboard the airplane. No further actions were reported. The investigation did not state any injuries or damage beyond the deployment of the slides.