There's a major cellphone outage that's hitting nationwide on Thursday morning, affecting AT&T and T-Mobile. 

Verizon also reported issues but said it was mostly due to trying to call people with other services who were having issues. 

It's also interfering with the ability of some police departments to receive 911 calls. 

It started early Thursday morning, and some people are just waking up to it now. 

It's affecting a lot of major metropolitan areas, including New York, Boston, Atlanta, Houston, Dallas, Los Angeles, Seattle and San Francisco. It's even hitting in Canada, in Montreal. 

AT&T seemed to have experienced the largest number of issues, with nearly 32,000 reports at around 4:30 a.m., according to data from DownDetector,  which tracks outages by collating status reports from sources including user-submitted errors on its platform.

More than 800 service outages were also reported on T-Mobile [....]

Others reported issues on smaller carriers including Boost Mobile, Consumer Cellular and Straight Talk Wireless.

Some AT&T customers had their phones stuck in "SOS mode." 

Some feared a cyber attack, with one techie saying he “can’t imagine this is incompetence or a single node failure.”

But they have not yet determined what the cause is.