The cause of the 911 outage Tuesday morning — which affected Butler County as well as five other counties — is being investigated.

Steve Bicehouse, director of county emergency services, said the outage, which lasted about an hour and a half in Butler, happened in the 911 phone system that covers Butler and other counties.

“This was not a Butler County specific issue,” Bicehouse said.

He said CenturyLink, which owns the 911 phone lines, and Air Bus, which provides the 911 equipment, is doing an investigation to find what caused the problem.

Bicehouse said the county 911 center experienced a partial outage for roughly an hour early Tuesday morning. Then at 7:15 a.m., the center experienced a full outage. He said service was restored at about 8:30 or 9 a.m.

During the outage, emergency services told people with emergencies to call the main office number rather than 911.

Six dispatchers were working at the time, and three of them were moved to offices at the 911 center so they could take calls. The remaining three stayed in the dispatch room to monitor the emergency radios.

Bicehouse said emergency services got five to 10 calls during the outage, and as far as he can tell, there was no impact on response times.

The outage also affected Armstrong, Cambria, Indiana, Somerset and Westmoreland counties at different times.