NASA said they lost contact with the ISS at 9:45 a.m. EST, during a software update to the space station's flight computers.
"Flight controllers in Houston were updating the software onboard the station’s flight computers when one of the station’s data relay systems malfunctioned, " NASA said.
"The primary computer that controls critical station functions defaulted to a backup computer, but was not allowing the station to communicate with NASA’s Tracking and Data Relay Satellites," NASA added.
All communications were restored nearly three hours later at 12:34 p.m. EST.
NASA spokesman Josh Byerly said during the outage, NASA was only able to communicate with the space station every 90 minutes, when it passed over Russian ground stations.
Byerly said the station, which currently has two American astronauts, one Canadian and three Russian cosmonauts on board, was not in any danger.
Officials said that though the loss of contact is not unprecedented, it remains a cause for concern and will continue to be investigated.
Just a few months ago, Russia lost the ability to send commands to most of its satellites and its segment of the ISS following a power cable failure near Moscow on Nov. 14, 2012.
The station is the product of a partnership among 16 nations and carries six laboratories for space research.