DHS Secretary Markwayne Mullin said it was due to a "telecommunications outage."
The Federal Aviation Administration ordered a rare nationwide ground stop Friday for all airports due to a communication issue affecting air traffic control.
Department of Homeland Security Secretary Markwayne Mullin told reporters it was due to a "telecommunications outage" and that there was no indication the incident was a "nefarious attack."
More than 1,000 flights have been canceled amid the issue.
The Federal Aviation Administration ordered a nationwide ground stop Friday for all airports due to a communication issue affecting air traffic control.
The agency's alert said the stop was "due to extraordinary circumstances and for reasons of safety."
AirSpace Intel, the contractor behind the SMART AI system that has been rolling out at facilities nationwide, put out a statement on X about the ground stop.
"The current ground stop is not based on or a result of the SMART system, any product of ASI or our integration with FAA and ATC," the company said.
-ABC News' Ayesha Ali and Clara McMichael
As of 6:04 p.m., 1,913 flights have been cancelled and 10,494 flights have been delayed nationwide amid the ground stop, according to FlightAware.
That number is expected to increase throughout the night as the telecommunications issue continues to persist.
Earlier Friday, Department of Homeland Security Secretary Markwayne Mullin told reporters that the federal government is investigating the incident and there was no indication yet that it was a "nefarious attack" and that everyone is safe.
"It's just a telecommunications outage as of now," he told reporters.
Mullin said the government will look into the root of the problem.
"This isn't another 9/11. I cannot repeat that enough," he added.
