The ground halt that effectively grounded all planes earlier on Wednesday morning has been removed, according to the Federal Aviation Administration of the United States. There have been severe delays at airports across the country due to a system failure.

“Normal air traffic operations are resuming gradually across the US following an overnight outage to the Notice to Air Missions system that provides safety info to flight crews. The ground stop has been lifted,” the FAA tweeted.

The agency has not immediately indicated what caused the outage but said, “We continue to look into the cause of the initial problem.”

A technical malfunction at the FAA resulted in the cancellation of all flights across the US. A Notice to Airmen stated that the impact on flights will probably be global.

The FAA had stated that no expected time of restoration was available and that flights would not be able to restart until the issue was fixed.

Then, until 9am ET, all airlines were required to halt domestic aircraft departures. No information has yet been released regarding any comparable broad suspensions on overseas planes that are waiting to depart for the US from abroad. The body claims that this is to “Allow the agency to validate the integrity of flight and safety information.”