Boeing stock (BA) closed down 2.3% on Monday as investigators looked into the crash of a South Korean Boeing jet.

On Sunday, a Jeju Air Boeing 737-800 crash-landed at Muan International Airport in South Korea. The jet skidded on its belly without its landing gear deployed, crashing into a concrete wall and killing 179 passengers. Only two flight attendants were the remaining survivors, the airline said.

Videos online also show what appears to be a bird strike affecting one of the jet’s two engines, which may have affected the plane’s approach to the airport in addition to possible issues with the landing gear.

The South Korean government said Monday it plans to conduct a safety inspection of all Boeing 737-800 aircraft operated by domestic airlines, Korea’s Yonhap News agency reported.

Yonhap News reported earlier that another Jeju Air jet returned safely to South Korea’s Gimpo Airport on Monday after it also had a problem with its landing gear after takeoff.

"We plan to implement rigorous aviation safety inspections in response to the [landing gear] incidents," Joo Jong-wan, aviation policy chief at South Korea’s transport ministry, said at a briefing.

In a statement posted online, Boeing said it was in contact with Jeju Air regarding the crash and that the plane maker was “ready to support them.”

Jeju Air has 38 737-800 jets in its fleet, per aviation site Planespotters. Other operators with the 737-800 model jet include T'way Air, with 27 aircraft; Jin Air, with 19; and Eastar Jet, with 10, per Planespotters and Yonhap News.

The 737-800 is an older iteration of Boeing’s 737 series of jets, which first flew in 1997 and was phased out for the 737 Max jets. Per aviation data firm Cirium, 180 airlines around the world use the 737-800 jet, and 4,400 737-800s are currently in use, making up 17% of the overall global commercial fleet.

Any concern regarding the safety of Boeing’s workhorse jet is a major problem for Boeing given recent safety issues. Earlier this year the FAA ordered the temporary grounding and subsequent production monitoring of Boeing 737 Max jets due to a door “plug” that flew off an Alaska Airlines plane midair in January.

This followed two fatal 737 Max crashes in 2018 and 2019 that together killed all 346 passengers and crew on board and led to a 20-month grounding of planes as safety changes were made. Critics blamed a defect in one of the plane’s safety systems for the crashes of the two 737 Max jets.

Pras Subramanian is a reporter for Yahoo Finance. You can follow him on X and on Instagram