Nine people remain missing after a UPS plane departing Louisville Muhammad Ali International Airport in Kentucky on Tuesday crashed, killing at least 12 people.

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.

The deceased are believed to include the three people aboard the plane, who were identified Thursday by UPS as Capt. Richard Wartenberg, First Officer Lee Truitt and International Relief Officer Capt. Dana Diamond.

The UPS plane whose engine exploded in Kentucky had flown out of Baltimore Marshall Airport less than 12 hours earlier.

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 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.

Captain Richard Wartenberg, First Officer Lee Truitt and International Relief Officer Captain Dana Diamond were those on board the flight, according to UPS. Friday, a family shared that two of its members, Louisnes Fedon and his young granddaughter Kimberly, were also among those who died after the plane went down.

A UPS cargo plane crashed at a Louisville, Kentucky, airport where the company operates its largest package delivery hub. UPS calls the giant center Worldport.

The crash of a UPS plane in Louisville, Ky., has disrupted the shipper's air cargo headquarters, delaying some deliveries.