US cyber watchdog agency CISA says it is working with AT&T to understand the cause of outage that disrupted calls and text messages as well as emergency services in major cities on Thursday.
In a statement, Eric Goldstein, CISA's executive assistant director for cybersecurity, said that the agency "is aware of the reports and we are working closely with AT&T to understand the cause of the outage and its impacts, and stand ready to offer any assistance needed."