Dozens of federal aviation investigators are on the ground in Louisville searching the crash site's debris field, which covers nearly a half-mile area.

By Allison Lampert (Reuters) -As a bell sounded in the cockpit, three UPS pilots tried to control a cargo flight that crashed this week in Louisville, Kentucky, killing at least 13 people, the National Transportation Safety Board said on Friday.

The UPS cargo plane crew tried to control the aircraft for about 25 seconds before it crashed into a ball of flames shortly after taking off on Tuesday.

The cockpit voice recorder captured a persistent bell that began about 37 seconds after the crew called for takeoff thrust, and the bell continued until the recording ended, an NTSB official said.

Investigators are reviewing 63 hours of data collected from the black box of a UPS cargo plane involved in a deadly crash that killed at least 13 people in Louisville, Kentucky, earlier this week. Nine people remain missing as authorities sift through the wreckage of Tuesday's crash in an attempt to piece together what went wrong.

A Louisville resident and several businesses filed a federal lawsuit Thursday against UPS and other companies after a fatal cargo plane crash in Louisville this week killed at least 13 people. The lawsuit claims the crash and fallout was the result of negligent and wanton conduct by UPS,

The grim task of finding victims from the firestorm that followed the crash of a UPS cargo plane in Louisville, Kentucky, has entered a third day.