Hundreds of Alaska Airlines flights and thousands of passengers’ travel plans were disrupted over the weekend and well into Monday following a “significant IT outage” that resulted in the grounding of planes for about three hours.

The outage was a result of an unexpected hardware failure in Alaska's data centers and is not related to cybersecurity issues, the airline said.

Alaska Airlines said its operations have resumed after a temporary ground stop was issued on all its flights and those of a regional subsidiary Horizon Air due to an IT outage affecting its operations,