A leak has been found on the Russian side of the International Space Station, according to NASA.

The leak was found at about 7 p.m. ET Wednesday by flight controllers in Houston and Moscow.

The flight controllers didn't think the crew was in immediate danger, so the decision was made to allow them to continue sleeping. But once they woke up Thursday morning, both Mission Control in Houston and the Russian Mission Control Center outside of Moscow began troubleshooting the source of the leak, according to NASA.

Checks determined the leak was coming from the Russian side of the orbital outpost, NASA said in a news release.

"The leak has been isolated to a hole about two millimeters in diameter in the orbital compartment, or upper section, of the Soyuz MS-09 spacecraft attached to the Rassvet module of the Russian segment. This is a section of the Soyuz that does not return to Earth," NASA said.

A special temperature-resistant tape called Kapton tape was used on the leak site, which slowed the leak some, NASA said. But flight controllers and the crew are trying to develop a more long-term repair.

Officials and flight controllers were continuing to monitor the situation, and the crew and the flight controllers will search for any more possible leaks.

NASA said the station and crew are fine.

"All station systems are stable, and the crew is in no danger as the work to develop a long-term repair continues," NASA said.

The six-crew members are:

NASA:
Commander Drew Feustel
Flight engineers Ricky Arnold
Serena Auñón-Chancellor

European Space Agency
Alexander Gerst

Russian space agency Roscosmos
Oleg Artemyev
Sergey Prokopyev