A Crew-11 member, who NASA has yet to identify, had an undisclosed medical concern that triggered the agency to accelerate their return to Earth.

NASA will discuss events that led to its decision to postpone the agency's first spacewalk of the year outside the International Space Station.

Crew-11—which includes two American astronauts, a Japanese astronaut and a Russian cosmonaut—splashed down in the Pacific Ocean off the coast of San Diego around 12:41 a.m. PT/3:41 a.m. ET after a nearly 10-hour journey.

A planned spacewalk outside the International Space Station was scrapped because of what NASA called a "medical concern" with an unidentified crew member.

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JOHNSTON SPACE CENTER — During an early morning press conference, NASA Administrator Jared Isaacman revealed on Thursday that a Crew-11 astronaut suffered a “serious medical condition” while onboard the International Space Station last week.

Two Americans and astronauts from Japan and Russia landed in a SpaceX capsule in the Pacific Ocean after a medical issue prompted NASA to move up their return to Earth.

For the 1st time in the history of the International Space Station, an astronaut experienced a health issue that required NASA to end a mission early.

NASA administrator Jared Isaacman said in a press conference that “a single crew member on board the [ISS] experienced a medical situation and is now stable,” but NASA is playing it safe and bringing Crew-11 home early.