Shares of Air Busan dropped on Friday, after a plane belonging to the budget carrier caught fire earlier this week.

South Korean officials are launching an investigation into the cause of the fire that engulfed an Air Busan passenger plane, with eyewitness accounts suggesting a power bank may have sparked the blaze.

An Airbus plane belonging to South Korean carrier Air Busan caught fire on Tuesday at Gimhae International Airport in the country’s south while preparing for departure to Hong Kong, fire authorities said.