GRAND RAPIDS (AP) — An upgrade to Michigan’s 911 emergency system caused a technical issue which resulted in early morning outages across the state. In the Upper Peninsula, the outage affected Delta, Schoolcraft, Menominee, Baraga, Houghton, Keweenaw, and Ontonogon counties.

A fiber optic line was being updated about 2:30 a.m. Friday when the system crashed and remained down for several hours, according to state police. It was restored about 7 a.m.

Many county dispatch centers used non-emergency lines as backup.

Service was restored to Grand Rapids 911 Dispatch Center, but police said “intermittent outages may be possible.” About 40 counties were affected by the outages, police said.

Kent County’s emergency communications manager told WOOD-TV that dispatchers first noticed the problem when a call would come in to the 911 line and no one could be heard on the other end.

Downtown Detroit and some other dispatch centers did not experience an outage because they use copper lines instead of fiber optic lines, according to state police Lt. Mike Shaw.