Throughout Virginia, 25 emergency 911 call centers — more than previously disclosed — lost critical services during the June 29 storm as a result of “failures and deficiencies” at Verizon, according to state regulators.

Outages in Northern Virginia alone affected 2.3 million people.

The report by the Virginia State Corporation Commission concedes that the storm, classified as a derecho, was severe. But the report, released Friday, says Verizon’s system was engineered and built to withstand such a storm and should have held up if the company’s maintenance and testing procedures had been followed beforehand and the utility had mounted a faster response.

The maintenance shortcomings raise concerns that the problems may be systemwide, according to regulators. Verizon was the only carrier in Virginia that had “significant 911 service problems,” the report says.

In August, Verizon said it had begun a systemwide review, and on Friday, Anthony Lewis, vice president for Verizon’s Mid-Atlantic region, said the company is ”diligently pursuing” the process.

Virginia’s report describes a problem that went beyond the troubles previously identified by Verizon and local emergency officials in Fairfax, Prince William and Arlington counties and in Manassas and Manassas Park.

Service came back at different times in those communities, but the emergency call sites generally could not receive 911 calls through most of June 30, and they did not regain the ability to link an address to a call until July 4, the report says. The address link “is an important component,” regulators said.

Elsewhere in Virginia, 20 other 911 centers lost the address link or lost backup telephone lines, the report says. Those sites included Alexandria and Herndon; Fauquier and Loudoun counties; the Metropolitan Washington Airports Authority; and Joint Base Langley in the Hampton Roads area.

The Virginia report reinforces Verizon findings that drained batteries, faulty generators and the failure of a technician to thoroughly explore the cause of troubles extended 911 problems that started at central offices in Arlington and Fairfax.

The report also says that two days before the storm, the generator at Verizon’s Arlington office failed to start during routine testing and was flagged for maintenance in a logbook.

Verizon previously said its backup systems had been tested and started in the days before the storm. Late Friday, Verizon spokesman Harry J. Mitchell, said the earlier statement “was based on our knowledge at the time. At our investigation proceeded, we found that, in fact, the generator did not successfully start.”

Some backup power systems also failed in less than five hours and an important system that provided Verizon with an overview of service outages had only a 30-minute power reserve, the report says.

Federal regulators also are reviewing the 911 outages, as is the Metropolitan Washington Council of Governments.