India, Oct. 12 -- A power bank catching fire mid-air. Passengers scrambling to contain the flames. An aircraft forced to divert. An incident that could have ended in tragedy unfolded aboard an IndiGo flight from Delhi to Chennai on Sunday, raising serious questions about compliance with aviation safety rules and the dangers of improperly stored lithium-ion batteries.

Flight 6E 6115 was diverted to Hyderabad after smoke was detected from a passenger's electronic device in the overhead luggage compartment. The cabin crew used a fire extinguisher to douse the flames, and the aircraft landed safely. IndiGo arranged an alternative aircraft to take passengers to Chennai.

A 36-second video from inside the cabin showed passengers initially atte...