This November 2014 image made from a frame grabbed from NASA-TV, shows Expedition 42 crew members, front row from left, Anton Shkaplerov, Samantha Cristoforetti and Terry Virts, and back row from left, Elena Serova, Commander Barry Wilmore and Alexander Samokutyaev, while on the International Space Station in the Zvezda service module during a traditional crew greeting ceremony with family and mission officials on the ground. Astronauts evacuated the U.S. section of the International Space Station and moved to its Russian module after a problem emerged Wednesday, Jan. 14, 2015. (AP Photo/NASA-TV)

The astronauts are back in the American side of the International Space Station.

Early Wednesday, the crew fled to the Russian segment after an alarm indicated a possible toxic leak. But NASA later said there was no leak of the ammonia coolant and a computer problem likely set off the false alarm.

By Wednesday afternoon, the astronauts had returned to the U.S. side.

When the alarms went off around 4 a.m., the crew followed emergency procedures—slapping on oxygen masks, taking cover in the Russian quarters, then sealing the hatches between the U.S. and Russian sides.

At the same time, flight controllers at NASA's Johnson Space Center in Houston turned off non-essential equipment.

In this Dec. 1, 2014, image provided by NASA taken during a training exercise, U.S. astronaut Terry Virts, left, assists European Space Agency astronaut Samantha Cristoforetti with emergency training aboard the International Space Station. Astronauts evacuated the U.S. section of the International Space Station and moved to its Russian module after a problem emerged Wednesday, Jan. 14, 2015. (AP Photo/NASA)

In this April 20, 2014, image made from a frame grabbed from NASA-TV, the SpaceX Dragon resupply capsule begins the process of being berthed on to the International Space Station. Astronauts hurriedly evacuated the U.S. section of the International Space Station and moved to its Russian module after a problem emerged Wednesday, Jan. 14, 2015, but Russian and U.S. officials insisted all six crew were not in any danger. (AP Photo/NASA-TV, File)

In this Nov. 23, 2014, file photo, U.S. astronaut Terry Virts, left, Russian cosmonaut Anton Shkaplerov, center and Italian astronaut Samantha Cristoforetti, crew members of the mission to the International Space Station, walk to the rocket prior to the launch of Soyuz-FG rocket at the Russian leased Baikonur cosmodrome, Kazakhstan. Astronauts hurriedly evacuated the U.S. section of the International Space Station and moved to its Russian module after a problem emerged Wednesday, Jan. 14, 2015, but Russian and U.S. officials insisted all six crew were not in any danger. (AP Photo/Dmitry Lovetsky, Pool, File)

Explore further Alarm sends astronauts to shelter at space station (Update)

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