The Federal Aviation Administration announced that the nationwide ground stop it issued earlier on Friday has been lifted, according to the AP.

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The Federal Aviation Administration issued a nationwide ground stop for all flights in the United States until further notice, "due to extraordinary circumstances and for reasons of safety."

This means that planes currently in the air may land, but those on the ground may not take off.

U.S. Homeland Security Secretary Markwayne Mullin told reporters Friday evening that there is currently no reason to suspect a national security threat is behind the communications outage affecting flights.

"There's no reason for the public to be afraid or scared for their loved ones," Mullin said.

"This is not another 9/11," he added. "This is a telecommunications outage; this is...