The crew of the International Space Station are "safe and in good shape" after being quarantined in the Russian segment of the craft.

The alarm occurred at 4:00 a.m. EST, but is now believed to be the result of a false sensor reading or a computer problem, as opposed to a leak of an ammonia coolant.

The incident occurred after flight controllers in Mission Control at NASA's Johnson Space Center in Houston noticed an increase in pressure in the station's water loop for thermal control system B and later a cabin pressure increase.

The crew isolation was a safety measure taken in case these occurrences indicated a serious situation such as an ammonia leak. During the incident some the U.S. segment equipment was also shut down.

"The crew received an update from spacecraft communicator James Kelly that it's starting to look like a false indication, either a faulty sensor or computer relay. Flight controllers are continuing to analyze the situation but for now, there is still no direct evidence that ammonia was leaked into the station atmosphere," NASA stated.

The crew is still isolated within the Russian segment of the ship.

"Hey everybody, thanks for your concern. We're all safe & doing well in the Russian segment. Follow @Nasa for updates on @Space_Station today,"Sam Cristoforetti, a crew member aboard the ISS, Tweeted at 7:04 a.m.

There are currently six crew member (part of Expedition 42) aboard the ISS: Commander Barry Wilmore; Flight Engineer Alexander Samokutyaev; Flight Engineer Anton Shkaplerov; Flight Engineer Terry Virts; Flight Engineer Samantha Cristoforetti; Flight Engineer Elena Serova.