What to know about the deadly UPS plane crash in Louisville, Kentucky

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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 searching for additional victims in 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, the NTSB's Todd Inman said.

Here’s what is known about the crash:

Photos showed one of the plane's sitting on the ground next to the runway after the crash, said John Cox the CEO of Florida-based aviation consulting firm Safety Operating Systems.

Cox said he could recall another instance when one of the same General Electric engines detached from a plane. That happened at Chicago’s O’Hare airport in 1979 and 273 people were killed. Investigators blamed improper maintenance before the crash.

The plane should have been able to take off if one engine was inoperable or even if it had fallen off, Cox said. But that may not have been possible if one of the other engines was damaged or there was other significant damage to the plane.

The NTSB will look into the full maintenance history of the UPS plane as well as the engines and other components, Inman said.

But he said UPS has told the agency that the flight was not delayed and that no maintenance was performed right before it took off.

Flight records suggest the McDonnell Douglas MD-11, built in 1991, underwent maintenance while it was on the ground in San Antonio for more than a month until mid-October. It's not clear what work was done.

Jeff Guzzetti, a former federal crash investigator, said it’s too early to know whether the problem at the time of the crash was in the engine, the structure that holds the engine, or something else.

“It could have been the engine partially coming off and ripping out fuel lines. Or it could have been a fuel leak igniting and then burning the engine off. it’s just too soon to tell,” he said.

Aviation attorney Pablo Rojas said video suggests the plane struggled to gain altitude as the flames blazed along its left side.

The plane, bound for Honolulu and fully loaded with fuel, shredded the roof of one large building before erupting in flames.

“There’s very little to contain the flames, and really the plane itself is almost acting like a bomb because of the amount of fuel,” he said.

He said it’s hard to know if the pilot saw the flames, and that even if the crew realized there was a problem, aborting the takeoff might have been dangerous.

The plane crashed in an area dotted with scrap yards and UPS facilities.

It narrowly missed a restaurant bar and went down not far from a Ford auto assembly plant where hundreds of people were working, Kentucky Gov. Andy Beshear said Wednesday.

The blaze stretched nearly a city block and destroyed much of the plane's fuselage, fire officials said.

Package sorting at UPS' mammoth handling facility in Louisville remained shut down Wednesday. How much the crash will disrupt shipping remains to be seen.

The hub — called UPS Worldport — handles 300 flights daily and sorts more than 400,000 packages an hour.

Flights at Louisville Muhammad Ali International Airport resumed Wednesday morning, although just one runway was open initially. More than a dozen flights were canceled.