AT&T customers in the D.C. area were unable to call 911 for hours Wednesday night because of a national outage.
Officials in D.C., Fairfax County, Prince George's County and elsewhere advised residents to call other phone numbers in the event of an emergency.
The outage lasted about two hours.
A representative for AT&T gave the following statement:
"We are aware of a service issue affecting some calls to 911 for wireless customers and we’re working to resolve it as quickly as possible. We apologize for this inconvenience."
The Federal Communications Commission will launch an investigation into what went wrong.
“Every call to 911 must go through,” FCC Chairman Ajit Pai said in a statement issued Thursday. "I announced last night that I have directed Commission staff to track down the root cause of this outage."
A representative of the D.C. Office of Unified Communications said AT&T was experiencing a "nationwide outage" and AT&T customers with an emergency should call 202-373-3700 with extension 1.
Alexandria police later said residents with an emergency should text 9-1-1 or call (703) 746-4444.
Prince George's County AT&T customers were also affected and advised to call 301-352-1243 for help, according to a representative of the county fire department. The county has since said 911 service is back to normal for AT&T customers.
Charles County officials also reported its residents were having issues and those with AT&T should call 301-609-3499 for emergencies.
Other parts of the country have reported similar issues, including Colorado, Florida, Indiana and Texas.
AT&T tweeted about 10:30 p.m. the "Issue has been resolved that affected some calls to 911 from wireless customers. We apologize to those who were affected."
AT&T National Outage May Affect 9-1-1 Service in Fairfax County https://t.co/NSmH4ZCucS
— Fairfax County (@fairfaxcounty) March 9, 2017
AT&T reporting sporadic 911 service disruptions nationwide. Call 9-1-1 via another cell carrier, use a landline to or dial (301) 279-8000.
— Montgomery County MD (@MontgomeryCoMD) March 9, 2017
*URGENT ADVISORY: AT&T mobile network users, please call 703-792-6500 if you experience an issue contacting 9-1-1 due to nationwide outage. pic.twitter.com/Ar5CbnuRMQ
— Prince William PD (@PWCPoliceDept) March 9, 2017
AT&T outage effecting the ability for AT&T customers to reach 9-1-1. AT&T customers call 301-352-1243 for emergency assistance.
— Mark Brady (@PGFDPIO) March 9, 2017
ALERT: Alexandria experiencing issues w/ AT&T carriers calling 911; if callers have emergency-TEXT 9-1-1 or call 703.746.4444 #ATTOutage ��
— Alexandria Police (@AlexandriaVAPD) March 9, 2017
We have been advised there is a nationwide outage for AT&T – for 911 AT&T customers should call 202-373-3700 ext 2.
— OUC Director (@OUCDirector) March 9, 2017
❗️Be advised that though the AT&T outage is nationwide, the 202 number for 911 is solely for emergencies in the District of Columbia. https://t.co/RPe8ibXsA7
— Mayor Muriel Bowser (@MayorBowser) March 9, 2017