Here's what we know:
Based on reports from law enforcement and government agencies, AT&T customers were unable to call 911 from their cellphones for a brief period Wednesday night. In many cases, police and sheriff's departments provided an alternate phone number for residents to use in case of an emergency.
The company declined to answer questions Thursday about the outage and instead issued a brief statement saying service had been restored to the affected customers.
In Arkansas, one sheriff's office shared a message it received from AT&T that blamed "a service outage that is impacting the ability to deliver AT&T Mobility wireless 911 calls in your area." The message noted there could be issues with 911 calls or certain "location information."
It's unclear, but likely thousands. Maybe millions.
Officials in Baltimore, Houston, Washington, D.C., and other cities reported the outage, along with authorities in more than a dozen states.
Several law enforcement agencies described the outage as "nationwide," and FCC Chairman Ajit Pai said on Twitter that his agency received reports of a widespread outage. An FCC spokesman said the agency was trying to determine how many people were affected but noted the investigation had just begun.
AT&T has 147 million wireless customers in the U.S. and Mexico, according to its website .
No. Large-scale 911 outages have happened in the past.
Wireless carrier T-Mobile had two separate outages on one day in August 2014 that together lasted three hours and affected all 50 million of its customers at the time, according to the FCC. The company reached a $17.5 million settlement with the FCC in 2015.
An outage...