Scores of people were killed on Sunday when a passenger plane crashed at an airport in southwestern South Korea, with the plane careening down the runway on its belly before bursting into flames.

According to the local fire department, at least 177 people have been confirmed dead so far. Two people, both crew members, were rescued alive from the crash site, leaving only two of the 181 people on board the aircraft missing.

It is the deadliest aviation disaster in South Korea since 1997, when a Korean Airlines Boeing 747 crashed in the jungles of Guam, killing 228 people.

What happened?

Jeju Air Flight 7C 2216 from Bangkok was carrying 175 passengers and six crew members when disaster struck at the airport in Muan county on the country’s southwestern tip just after 9 a.m. local time on Sunday (7 p.m. ET Saturday).

Footage of Sunday’s crash, broadcast by several South Korean news agencies, showed the plane skidding on its belly at high speed, hitting an earthen embankment and exploding in a fireball.

In the footage broadcast by networks including YTN, JTBC and MBC, neither the rear nor front landing gear could be seen as smoke poured from the tail of the skidding plane.

Firefighters were later seen using water cannons to extinguish the burning wreckage of the plane, listed on flight tracking site FlightAware as a Boeing 737-800. Several pieces of the aircraft were also seen scattered on the runway.

According to the South Jeolla Fire Department, the victims include 82 men, 83 women and 12 people whose gender could not be determined. According to the rescue team, both survivors were crew members, a man and a woman.

According to the South Korean Land Ministry, two Thai nationals were among the passengers. All other passengers were South Koreans.

What caused the accident?

Experts told CNN that the plane’s landing gear – particularly the takeoff and landing wheels – did not appear to be fully extended before landing. But what caused this deployment failure is still unclear.

Aviation analysts said more evidence was needed before South Korean authorities could finally determine what may have caused Sunday’s crash, including speculation by local officials about a possible bird strike before the crash landing.

The comments came after Muan Fire Department chief Lee Jeong-hyun informed the media that the cause was “estimated to be a bird strike or bad weather.” Footage of the crash showed clear skies at the time.

David Soucie, a former Federal Aviation Administration safety inspector, said: “Speculation is an investigator’s worst enemy.”

“That’s why the information is so protected when investigating an aircraft accident. “You shouldn’t speculate about things like this,” Soucie told CNN’s Paula Newton.

Aviation industry consultant Scott Hamilton echoed Soucie’s concerns and called on South Korean authorities to “stop making any more declarative statements at this time.”

Sunday’s crash was “very confusing” considering that both the plane and the carrier had a strong safety record and flying conditions were excellent, an aviation journalist said.

The Boeing 737-800 is one of the most widely used aircraft in the world and each one is used for about four to five flights per day, Geoffrey Thomas, editor of Airline News, told CNN’s Paula Newton.

“It is the most reliable aircraft in the world and has been in service for 20 years,” he said. “Everyone knows how it works. And it works really, really well. And the maintenance done in (South) Korea is as good as anywhere in the world.”

“It’s a little unclear whether the landing gear collapsed upon landing or whether the landing gear wasn’t extended at all. “This is a really serious issue that investigators are obviously going to be very focused on,” Thomas added.

He added: “It is baffling” that the crash happened as the landing took place in dry and sunny conditions at a good airport.

US aviation giant Boeing has had a turbulent time in recent years, including two 737 Max crashes, a tragedy for which the company agreed to plead guilty to misleading the Federal Aviation Administration during the plane’s certification process .

However, analysts have described the Boeing 737-800 – an earlier and different model than the Max – as a reliable workhorse of the skies with an extremely strong safety record.

Jeju Air’s chief executive said the plane showed “no signs of problems” before Sunday’s accident.

“At present, it is difficult to determine the cause of the accident and we have to wait for the official announcement of the investigation by the relevant government agency,” Kim Yi-bae said during a press conference at the airport.

Where is the focus of the investigation?

Officials from the National Accident Investigation Board had arrived to investigate the cause of the accident.

According to a land ministry briefing, the control tower had instructed the pilot to change course and land in the opposite direction to avoid a possible bird strike. The pilot followed the instructions.

About a minute later the pilot called the tower. According to the ministry, the landing attempt took place about two minutes after the emergency call. The authorities are continuing their investigation.

The “black box” flight data recorder has been recovered by the accident investigation board, while the voice recorder has not yet been recovered, ministry officials said.

The flight data recorders or so-called “black boxes” provide aviation safety investigators with important facts when classifying an incident.

More than 700 police, military and coast guard personnel have been mobilized for on-site operations, the ministry added.

What do the authorities say?

South Korea’s acting president said the site of Sunday’s plane crash had been declared a special disaster area and promised a full investigation into the cause of the deadly disaster.

“We will focus all resources on the recovery and support of the victims. All necessary resources are being mobilized and a special disaster area has been declared,” Choi Sang-mok said in a statement.

Choi, who traveled to the crash site on Sunday, expressed his “sincere condolences” to the bereaved families and vowed to make every effort to deal with the aftermath of the incident and prevent similar accidents in the future.

The tragedy comes just two days into Choi’s acting presidency, the latest chapter in a period of political chaos in South Korea.

The country’s current president, Yoon Suk Yeol, was stripped of his powers by parliament two weeks ago after a short-lived martial law plunged the country into political chaos. He is currently suspended while a high court decides his fate.

Han Duck-soo, the man who replaced Yoon as acting president, was impeached by parliament on Friday, meaning Choi – the finance minister and deputy prime minister – was filling in for him.

What did the manufacturer of the plane say?

Boeing expressed its condolences to those who lost loved ones in the crash.

“We are in contact with Jeju Air regarding Flight 2216 and stand ready to support them,” Boeing said in a brief statement posted on its X account.

“We extend our deepest condolences to the families who lost loved ones and our thoughts are with the passengers and crew,” the company added.

The US aviation giant has had a turbulent time in recent years, including two 737 Max crashes, a tragedy for which the company agreed to plead guilty to misleading the Federal Aviation Administration during the plane’s certification process.

However, analysts have described the Boeing 737-800 as a reliable workhorse of the skies with an extremely good safety record.

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