The grim task of finding and identifying victims from the firestorm that followed a UPS cargo plane crash in Louisville, Kentucky, entered a third day Thursday as investigators gathered information to determine why the aircraft caught fire and lost an engine on takeoff.

The inferno consumed the enormous plane and spread to nearby businesses, killing at least 12 people, including a child and three UPS crew on the plane, and ending any hope of finding survivors in the crash at UPS Worldport, the company’s global aviation hub.

Louisville Mayor Craig Greenberg described the scene as “horrific,” with charred, mangled metal and “still some smoke rising from piles of debris.”

Meanwhile, UPS Worldport operations resumed Wednesday night with its Next Day Air, or night sort, operation, spokesperson Jim Mayer said.