(Reuters) -UPS on Friday said it has grounded its fleet of McDonnell Douglas MD-11s, the type of plane involved in Tuesday's crash in Louisville, Kentucky, which killed at least 13 people.

"Out of an abundance of caution and in the interest of safety, we have made the decision to temporarily ground our MD-11 fleet," a UPS spokesperson said in an emailed statement to Reuters. MD-11s account for about 9% of the company's fleet, the spokesperson added. The grounding is effective immediately.

The news was first reported by NBC News.

On Tuesday night, a UPS cargo plane bound for Honolulu crashed just after takeoff at Louisville International Airport. On Friday, U.S. safety investigators said as a bell sounded in the cockpit, three UPS pilots were trying to control the cargo flight.

While UPS flight 2976 started uneventfully, a repeating bell was heard on the aircraft's cockpit voice recorder just 37 seconds after the crew called for takeoff thrust, National Transportation Safety Board member Todd Inman told reporters.

Boeing, which owns the MD-11 program since its 1997 merger with McDonnell Douglas, and FedEx , which also operates MD-11 planes for cargo operations, did not immediately respond to Reuters requests for comment.