LOUISVILLE, Ky. (AP) — UPS announced late Friday that it would ground its fleet of MD-11 planes out of an abundance of caution following a deadly crash at its global aviation hub in Kentucky.

The MD-11 aircraft comprise about 9% of the company's airline fleet. We made this decision proactively at the recommendation of the aircraft manufacturer, the statement read. Nothing is more important to us than the safety of our employees and the communities we serve. The grounding of the fleet will be temporary, although the timeline remains uncertain.

The crash on Tuesday at UPS Worldport in Louisville, Kentucky, resulted in the deaths of 14 people, including three pilots who were aboard the MD-11 bound for Honolulu.

According to National Transportation Safety Board member Todd Inman, the cargo plane was just about to lift off when a bell rang in the cockpit. For the next 25 seconds, the pilots struggled to control the aircraft, which was barely airborne with flames engulfing its left wing and missing an engine before it crashed spectacularly.

Inman noted that it would take months before a transcript of the cockpit recording is made public. Meanwhile, Jeff Guzzetti, a former federal crash investigator, suggested that the alarm likely indicated an engine fire, occurring when the aircraft was at a critical point of takeoff.

UPS operates its Worldport hub with over 20,000 employees, managing approximately 300 flights daily and sorting over 400,000 packages every hour. UPS Worldport resumed operations on Wednesday night with its Next Day Air service.