FBI and Homeland Security 'urgently investigating' whether AT&T outage was a CYBERATTACK

Federal agencies are 'urgently investigating' whether the massive cellular outage that plagued Americans on Thursday was a cyberattack.

The Federal Federal Bureau of Investigation (FBI) and Department of Homeland Security (DHS) are on the hunt to track down what disrupted service AT&T, Verizon, T-Mobile and a dozen other cellular providers.

While the agencies have not shared details, a security expert told DailyMail.com that the outage has hallmarks of a hack.

Lee McKnight, associate professor at Syracuse University in New York, said the widespread nature appears to be 'a massive Distributed Denial of Service (DDOS) attack on core Internet infrastructure.'