Spokane County 911 operators continued to work out of a backup communications center following Monday’s system failure of the main emergency calling system.

Phone lines for 911 and Crime Check, the non-emergency police assistance line, went dead Monday about 6:40 p.m. When two backup systems also failed, operators were sent to the county’s backup communications center about nine miles away, north of Spokane. Callers could not get through to 911 operators for nearly 40 minutes.

Phone technicians from CenturyLink on Tuesday continued work to fix systems that failed at the main emergency communications center at 1620 N. Rebecca St. Kerry Zimmer, a CenturyLink marketing development manager based in Spokane, said it remains unclear what caused the problem.

“It’s a priority for us to determine what happened,” she said.

Lorlee Mizell, director of 911 Emergency Communications, said the primary system is back in operation, but the backup systems at the main communications center still aren’t working. She said operators will continue working at the reserve 911 center until all the systems are fixed.

“We don’t want to take any chances,” she said.

The 911 system handles the emergency calls for all police and fire departments countywide and is overseen by Spokane County.

Early indications are that the outage occurred during a slow period.

Spokane Fire Chief Bobby Williams, Spokane police Chief Frank Straub and Spokane Valley Fire Chief Mike Thompson said Tuesday that they were unaware of any specific incidents that emergency crews were late in getting to as a result of callers struggling to get through to 911.

Officials said that while the outage of multiple systems at the same time was concerning, they were impressed with the rapid activation of the backup center.

“It actually worked rather seamlessly,” Straub said.