Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Took Evasive Action; General Evacuated; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
While waiting for the completion of an anti-ice MEL (at the gate with jet bridge connected) I heard a commotion in the cabin. I stepped into the flight deck entry and heard there was some type of explosion. I immediately asked my FO (First Officer) to call for CFR. The #1 FA (Flight Attendant) was making a PA to evacuate. I assisted him as best I could while trying to determine what had happened. As soon as possible I turned off the APU and the batteries to remove any power issues that may have caused the explosion. I also turned on the emergency exit lights to aid with the evacuation. Emergency exit light battery exploded. It would help to have both a FA and crew ground evacuation checklist onto the jet bridge. Given we had no ground power and the issue was electric the use of the megaphone would have been helpful if the #1 FA could have gotten it before the passengers started to leave the aircraft.
Captain reported that during a maintenance action to MEL an Anti Ice problem; and emergency exit light battery pack exploded; causing the aircraft to be evacuated and CFR to be called.