The Federal Communications Commission (FCC) is launching an investigation into the nationwide CenturyLink internet outage that disrupted access to 911 lines.

FCC Chairman Ajit Pai announced on Friday that he had directed the agency’s Public Safety and Homeland Security Bureau to probe the “cause and impact of this outage.”

“When an emergency strikes, it’s critical that Americans are able to use 911 to reach those who can help,” Pai said in a statement. “The CenturyLink service outage is therefore completely unacceptable, and its breadth and duration are particularly troubling.”

A CenturyLink spokeswoman did not immediately respond when asked for comment.