B737-700
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 342
Aircraft Equipment Problem Less Severe
Flight Crew Returned To Gate; General Maintenance Action
Aircraft
While taxiing into position on [the] runway; another aircraft reported flames coming out of our Number 1 engine. We taxied clear; shut down the engine; informed the Flight Attendants; and returned to the gate.
B737-700 Captain reported returning to the gate after another aircraft reported flames coming from the Number 1 engine during taxi.