SEATTLE — Some emergency 911 calls to dispatch centers throughout Washington and parts of Oregon failed to go through in the early morning hours Thursday because of a problem with the system operated by CenturyLink, the phone company and emergency officials said.

Service was restored by 6:30 a.m. in Oregon and 8 a.m. in Washington, said Kerry Zimmer, a CenturyLink spokeswoman in Spokane.

There were no reports of emergencies where people could not get help because of the outage, said Zimmer and Washington state Emergency Management Division spokeswoman Wendy Freitag.

“I guess overnight was a good time,” for an outage, Zimmer said. “But no 911 outage is good.”

The service to dozens of emergency dispatch centers is a priority because of the safety issue, Zimmer said. CenturyLink serves all the centers because they are linked.

A problem was first reported about 1:30 a.m. at Sheridan, Ore. The problems in Oregon and Washington were isolated and not connected, Zimmer said.

The cause of the outages is unknown and Zimmer couldn’t speculate on whether it could be computer hacking or an equipment problem. At some centers a phone line or two continued to work; at others, all the lines were not working.

During the outage, people with emergencies were advised to use a cellphone, which sometimes worked better than a land line. They also could try non-emergency numbers for dispatchers.

Some were posted on state highway department reader boards.

People also were advised to go to a fire station in person if they could not call for help.

The state Emergency Management Division, which coordinates dispatch centers and makes contingency plans, will look into what went wrong, said Freitag.

“Is there some vulnerability or gap we need to fill? I’m sure it will be done very thoroughly in this case,” she said.

In Seattle, the King County Office of Emergency Management also plans to have a long talk with CenturyLink to prevent this from happening again, said spokeswoman Marlys Davis.

There are fewer 911 calls overnight, but “sometimes those can be the most critical calls,” she said.