Federal investigators looking into the deadly UPS cargo plane crash in Kentucky will closely examine the aircraft's maintenance records and engines after finding that one of its engines fell off during takeoff.

The plane crashed and burst into flames Tuesday in Louisville, killing at least 11 people. The disaster also shut down the largest UPS package distribution hub and disrupted some flights in and out of the airport in Kentucky’s largest city.

Gov. Andy Beshear said Wednesday that a handful of people remained unaccounted for, and crews were continuing to search for victims an industrial area next to the airport where the plane slammed into businesses.

Three of those who died were on the plane, while the others were on the ground, officials said. Nearly 20 people were injured.

A team of National Transportation Safety Board investigators arrived on site Wednesday. Initial findings showed that the left wing caught fire while the plane was rolling toward takeoff, and its engine fell off, according to NTSB.