Delta had a 727 years ago in SLC catch fire. They had pre boarded a elderly couple in coach and about half a dozen passengers in first. The SO was the only pilot onboard. He heard a pop and smelled smoke. Smoke was visible in the forward galley. He told the flight attendants to evacuate and went to the cockpit to grab a fire extinguisher. On his return to the galley flames were curling up the sidewalls to the ceiling. He gave up on the fire extinguisher idea and started to exit the jetway when he noticed the ederly couple still sitting in coach. They had been left. He went back and told them to get out the aft airstair. He turned back around to see if other passengers had been left as black smoke reached him. He inhaled once and was almost incapacitated. It knocked him right to his knees. He barely managed to roll out a overwing exit.