Regional Jet 700 ER/LR (CRJ700)
Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Situational Awareness; Time Pressure; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Departure Airport; Flight Crew Inflight Shutdown
Aircraft
On departure out of ZZZ through about 400 ft. AGL we received the master warning and left engine fire indication. My First Officer was flying and I ran the QRH and he operated the radios and flight controls. ATC gave us left traffic and we ran the QRH; [requested ATC assistance]; briefed the flight attendants; announced to the passengers and performed a flaps 20 landing.I have no exact assumption as to what caused the fire in the left engine.  My best guess is from my experience is the bleed air broke off the valve and created emended heat in the cowl.Having a fire on an airplane is probably the most frightening thing I have ever encountered in my life. I am thankful that our crew; ATC; Crash Fire Rescue; and the flight attendants all did our best that day and there was no harm to any crew or passengers or further damage to the airplane.
CRJ-700 Captain reported an engine fire indication; resulting in an engine shutdown and return to the departure airport.