(This story was updated to accurately reflect the most current information.)

As the community in Louisville, Kentucky, mourns the loss of at least a dozen people killed in a fiery United Parcel Service cargo plane crash, authorities warned that answers for family members may still be a way off.

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.

Nine people are still unaccounted for, Louisville Mayor Craig Greenberg said on Nov. 6. The death toll could continue to grow as a slow search for a cause begins, officials said.

“There’s so much debris there. There’s so much charred, mangled metal that not all the bodies may have been located until you look underneath certain things, so that is going through the various layers of debris on the field," Greenberg said.

At least nine people are believed to have been killed on the ground, including a child, in addition to the plane's three crew members who are presumed to be dead, according to authorities. Due to the extent of the damage, Kentucky Gov. Andy Beshear said coroners may have difficulty identifying bodies.

Also delaying the process is the sheer size of the wreckage that search crews need to comb through to look for potential victims, a process that could take several days, authorities said.

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.

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. At the time of the crash, the plane was 475 feet above the ground and was flying at about 211 miles per hour, Inman said.

Here's what we know so far:

NTSB releases photos of recovered 'black boxes'

The National Transportation Safety Board 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 said Nov. 6 that investigators recovered the plane's recorders intact amid the crash debris and successfully retrieved data from the system, including cockpit audio. Inman said the NTSB will release a transcript of audio and prepare a timeline of the crash, but he warned the process of going through the data would be "laborious."

About 28 members from the NTSB arrived in Louisville on Nov. 5 to begin their investigation, according to Greenberg. The NTSB said the Federal Bureau of Investigation was assisting 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."

Louisville plane crash witnesses grapple with what they saw

Sadit Aliyev and a coworker were settling in just after 5 p.m. at Kentucky Truck Parts & Service to have a bite to eat when the explosion happened.

“As soon as the explosion happened, it knocked me off my feet,” Aliyev, who owns the automotive store said as he attempted to get back to the business to assess the damage. “I was thinking it was my last moments, that’s why I started recording the video.”

Aliyev’s footage is harrowing. The two-minute clip shows the plane slide across the ground, leaving a trail of fire and billowing smoke just outside the auto repair shop. The smoke plume grew for hours, placing all of the city and the surrounding region under a shelter-in-place order for much of the evening.

“When you’d come outside, the heat of the flames and fire was so bad,” he said.

"I feel empty. That’s what I feel like. It’s tragic. People died.”

— Monroe Trombly and Lucas Aulbach, Louisville Courier Journal

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 that serves 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. The full inquiry is expected to take a year or more to complete.

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. The airport's 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 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: Karissa Waddick, USA TODAY; The Louisville Courier Journal; Reuters

This article originally appeared on USA TODAY: Who are the victims of UPS plane crash? Crews face 'apocalyptic' scene.

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

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