The Federal Communications Commission (FCC), Department of Homeland Security (DHS) and FBI are investigating widespread outages in AT&T’s wireless network that affected customers across the country Thursday morning.

The FCC said it is aware of the reported outages and its Public Safety and Homeland Security Bureau is actively investigating the incident. 

“We are in touch with AT&T and public safety authorities, including FirstNet, as well as other providers,” the agency said in a post on X, formerly known as Twitter.

White House national security communications adviser John Kirby said the DHS and FBI are also looking into the incident and working with network providers to “see what we can do from a federal perspective to lend hands to their investigative efforts.”

“We’re going to look at this really hard,” he told reporters Thursday. “We’re going to work with industry to see what we can see we can find out, but right now, we’re being told AT&T has no reason to think that this was a cybersecurity incident.”

Kirby added he was not aware of any “chatter” coming from state or nonstate actors ahead of the outage.

The outages appeared to start around 4 a.m. EST, with more than 70,000 outages reported by 8 a.m., according to the tracking website DownDetector. The outages were mostly concentrated in Houston, Atlanta, Miami and Chicago but affected customers across the country.

By midmorning, AT&T said that three-quarters of its network had been restored, noting its teams took “immediate action” and were “working as quickly as possible to restore service to remaining customers.”

Alex Gangitano contributed.