Regional officials are calling for Verizon to strengthen its 911 emergency phone services after a system failure that affected millions of Northern Virginians after a severe storm last June.

"The impact of the storm on our region was significant. It was the single most important 911 outage in the 45-year history of 911," said Steve Souder, director of the Fairfax County Department of Public Safety Communications.

The Metropolitan Washington Council of Governments put together a group in July to investigate why the system failed, and its board approved the final report on Wednesday.

When a severe "derecho" storm knocked out power in the Washington area on June 29, two Verizon generators failed, battery backups drained and technicians did not identify the problem for hours. That led to 911 service failures in Northern Virginia, including complete failure in Fairfax County, Prince William County and the cities of Manassas and Manassas Park.

Some of those outages lasted more than five days, and Souder said the failure meant that 2 million people could not reach 911.

"911 is the first step of a long chain, and as someone said earlier today, it was a weak chain," Souder told The Washington Examiner after presenting the report. "Clearly, there's work that has to be done there, and I think in fairness, there has been some work achieved."

The COG group found that Verizon had not fixed previous maintenance issues with the generators that failed, did not fix the generators during the outage, and did not communicate adequately with the public. The report recommended that Verizon perform an independent audit of its 911 service and update its communication with the public and with 911 center agencies.

The Federal Communications Commission and the Virginia State Corporation Commission, which have also studied the incident, would be responsible for enforcing any new regulations on the utility.

Verizon spokesman Harry Mitchell said the company had launched its own audit into the power for its 911 facilities, improved its communication with public safety officials and increased its employee training.