Days after a United Parcel Service cargo plane crash caused a deadly fireball in Louisville, Kentucky, authorities fear the death count could keep growing as a slow search for answers begins.

At least 12 people were killed and multiple others were injured in the Nov. 4 crash, officials said. Officials described an "apocalyptic" scene, recounting the falling debris and a blackened sky over Louisville in the moments after the crash.

As of Nov. 5, at least nine people were confirmed to have been killed on the ground, in addition to the plane's three members who are believed to be dead, according to authorities. Due to the extent of the damage, Gov. Andy Beshear said coroners may have difficulty identifying the bodies.

Beshear has warned that the death toll could grow as authorities do not expect to find any survivors at the crash site. Earlier on Nov. 5, the governor said 16 families had reported loved ones who were unaccounted for.

"I'm deeply saddened to share that the death toll has risen to 12, with several individuals still unaccounted for," Louisville Mayor Craig Greenberg said in a statement on social media Nov. 5. "No one should face tragedy alone. Please take a moment to hug your loved ones and check on your neighbors."

Meanwhile, an investigation into the crash produced some preliminary findings about what went wrong.

Todd Inman, a member of the National Transportation Safety Board, confirmed during a news conference on Nov. 5 that a large plume of fire erupted around the plane's left wing and one of its three engines detached as the aircraft rolled down the runway.

About 28 members from the National Transportation Safety Board arrived in Louisville on Nov. 5 to begin their investigation, according to Greenberg. The NTSB said the Federal Bureau of Investigation was assisting the agency at the scene with collecting evidence, taking photographs, mapping and measuring the wreckage field, and "generally serving as a force multiplier for the NTSB go team."

Here's what we know about the investigation:

NTSB releases photos of recovered 'black boxes'

The NTSB on Nov. 6 released photos of the downed plane's so-called "black boxes": the flight data recorder and cockpit voice recorder. The boxes, which are typically brightly colored despite the name, appeared blackened by fire or smoke exposure in the photos.

Inman previously said investigators recovered the plane's recorders intact amid the crash debris on Nov. 5, adding that investigators should be able to retrieve data from the system within days.

Where did the UPS plane crash occur?

The plane crashed in a largely industrial area just south of the Louisville Muhammad Ali International Airport, about 6 miles south of downtown Louisville. The airport is home to UPS Worldport, an international air hub serving more than 300 daily inbound and outbound flights, and processes about 2 million packages each day.

Beshear said that two businesses were directly affected by the catastrophic crash – Kentucky Petroleum Recycling and Grade A Auto Parts. Other businesses, including a nearby convention center, restaurant and Ford Assembly Plant, escaped the blaze.

The crash and ensuing fires also disrupted airport-based operations at the UPS Worldport facility and slowed delivery services. UPS said it resumed operations at the facility on the evening of Nov. 5.

What caused the UPS plane crash?

The Federal Aviation Administration said the National Transportation Safety Board will lead the probe that will investigate the crash. Expect the full results of the inquiry to take a year or more.

The plane's flight data recorder and cockpit voice recorder will be a key part of the investigation.

"We feel comfortable that once we get these to our lab in (Washington) D.C. that we will be able to get a good readout of the applicable data, and that will be yet another point of information that will really help us understand what happened," Inman said.

Inman noted that the NTSB is “not aware” of any staffing shortages due to the government shutdown at the time of the crash. "SDF tower, from what we can see and what we've been told, was at its proper complement,” he said.

The aircraft, a 34-year-old MD-11 freighter, was carrying three crew members aboard when it crashed just after clearing a fence at the end of the runway during takeoff on Nov. 4. The plane hit nearby structures, including a petroleum recycling facility that was set ablaze and exploded, before erupting into flames.

Contributing: Jeanine Santucci and Karissa Waddick, USA TODAY; Reuters

This article originally appeared on USA TODAY: Deadly UPS cargo plane crash death count could rise, authorities fear

Reporting by Thao Nguyen and Jeanine Santucci, USA TODAY / USA TODAY

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