Witnesses to a deadly plane crash in South Korea on Sunday said they observed flames in the engine of the aircraft and heard explosions, according to a report.

A Jeju Air flight skidded off a runway at Muan International Airport in the town of Muan, roughly 190 miles south of Seoul, and collided with a concrete fence, killing at least 176 people, the Associated Press reported, citing the country's National Fire Agency (NFA).

Authorities are investigating a potential landing gear failure stemming from a bird strike that may have caused the crash, according to Yonhap News Agency. 

Videos show the plane attempting to land without its landing gear deployed.

PLANE VEERS OFF AIRPORT RUNWAY IN SOUTH KOREA AND CRASHES, KILLING AT LEAST 176: REPORTS

The flight was carrying 181 people when the collision happened at about 9:03 a.m. local time. Emergency workers pulled two crew members to safety who health officials say are conscious and not in life-threatening condition, while three people remained missing.

South Korea's Transport Ministry said the plane was a 15-year-old Boeing 737-800 jet that was returning from Bangkok in Thailand.

"We are in contact with Jeju Air regarding flight 2216 and stand ready to support them," Boeing said in a statement. "We extend our deepest condolences to the families who lost loved ones, and our thoughts remain with the passengers and crew."

One witness, Yoo Jae-yong, 41, who was staying at a rental house near the airport, said he saw a spark on the plane's right wing before the incident, according to Yonhap News Agency.

"I was telling my family there was a problem with the plane when I heard a loud explosion," Yoo said.

Another witness, identified only by his last name, Cho, told the outlet he was taking a walk 4.5 kilometers, or about 2.8 miles, from the airport when the plane crashed into the concrete wall at the end of the runway.

"I saw the plane descending and thought it was about to land when I noticed a flash of light," Cho said. "Then there was a loud bang followed by smoke in the air, and then I heard a series of explosions."

Kim Yong-cheol, 70, said the plane was unable to land in the initial attempt and had to circle back around to try again before the crash occurred.

Kim said he heard the sound of "metallic scraping" twice about five minutes before the crash. He also said he looked up at the sky and observed the plane ascending after failing to land before he heard a "loud explosion" and noticed "black smoke billowing into the sky."

KAZAKHSTAN PLANE CRASH SURVIVORS SAY THEY HEARD BANGS BEFORE AIRCRAFT WENT DOWN; PUTIN ISSUES STATEMENT

A 50-year-old witness, identified by his last name, Jung, was fishing nearby when he says he observed a flock of birds colliding with the plane, which resulted in a fire in the right engine.

"As the plane was landing on the runway, it hit a flock of birds approaching from the opposite direction," he said. "I heard two or three bangs as if the birds had been sucked into the engine before I saw flames coming from the right engine."

Kerati Kijmanawat, the director of Airports of Thailand, said in a statement that the plane departed from Suvarnabhumi Airport with no reports of abnormal conditions with the aircraft or on the runway.

Jeju Air said in a statement it expresses its "deep apology" over the crash and that it will do its "utmost to manage the aftermath of the accident."

The Associated Press contributed to this report.