A repeating bell sounded in the cockpit for 25 seconds as pilots tried to control a UPS cargo plane that caught fire in its left wing, had an engine fall off and crashed during takeoff this week in Louisville, Kentucky, a National Transportation Safety Board member said Friday.

The cockpit voice recorder captured a persistent bell that began about 37 seconds after the crew called for takeoff thrust, and the bell continued for 25 seconds until the recording ended, which investigators believe was the final point of impact, NTSB member Todd Inman said.

NTSB member Todd Inman Inman said there could be different types of alarms with varying meanings, but investigators know there was a fire occurring and will use flight data to help determine a clearer picture of what happened.

The crash Tuesday at UPS Worldport, the company’s global aviation hub in Louisville, killed 13 people, including the three pilots on board.

The NTSB is leading the investigation. Inman said it would be months before the transcript of the cockpit recording is made public as part of that investigation process.

Dramatic video captured the aircraft crashing into businesses and erupting in a fireball. Footage from phones, cars and security cameras has given investigators visual evidence of what happened from many different angles.