The man who killed 12 people in a municipal building on Friday in Virginia Beach, Va., fired many rounds — "well into the double digits" — and when officers caught up with the suspect, it took a "long gun battle" to stop him, according to Police Chief James Cervera.
One reason may have been the suspect's gear.
Authorities recovered a .45-caliber handgun with multiple extended magazines that were emptied, Cervera said at a weekend news conference. "The suspect was reloading extended magazines in that handgun, firing at victims throughout the building and at our officers."
An extended magazine is essentially a metal sleeve that holds more bullets than a gun's normal capacity.
"It allows someone to shoot more rounds before they're forced to reload the gun," says former ATF special agent David Chipman, who's now a senior policy adviser for the Giffords Law Center to Prevent Gun Violence.
The center is named for former congresswoman Gabby Giffords, who was nearly killed in 2011 by a gunman using a pistol equipped with a 33-round magazine.
Chipman believes extended magazines increase the deadliness of inexperienced shooters, especially those who haven't practiced reloading under fire.
"We did not carry [extended magazines] on the SWAT team," Chipman says. "But they do transform someone determined to kill into being much more efficient at doing that."
Extended magazines have been used at some of the worst shootings in recent American history, including Sandy Hook. A 2013 investigation by Mother Jones looked at 62 mass shootings, and found high-capacity magazines were used in at least half.
But other firearms experts aren't convinced the magazines are that important. "The type of magazine means nothing to the potential threat," says Thor Eells, a retired SWAT commander from Colorado Springs, Colo., now executive director of the National Tactical Officers Association.
He says modern semi-automatic handguns are very quick and easy to reload, so the size of the magazine doesn't give an attacker that much of a practical advantage over police.
Eells says it's "plausible" that mass shooters often opt for extended magazines, believing they may compensate for their lack of skill with the firearm. But he says the reality is that a high-capacity magazine may actually become a hindrance, by jamming.
While there have been repeated calls for federal restrictions on extended magazines in recent years, the attachments have been essentially unregulated since the federal "Assault Weapons Ban" expired in 2004.
There are restrictions in about 1/5 of the states, including California, which in 2000 banned new sales of magazines that hold more than 10 rounds. A 2016 ballot initiative went further, banning even the ownership of high-capacity magazines that had been purchased legally.
Gun rights groups challenged the California law, and in March a federal judge agreed with them that ban was unconstitutional. In his opinion, Judge Roger Benitez determined that the magazines qualified as "arms," and are covered by the Second Amendment.
"I was a bit surprised, but I was pleased," says Michael Hammond, of Gun Owners of America. He says the ruling gives him hope that the new conservative tilt of the Supreme Court will similarly protect the rights to own guns and accessories.
Hammond sees efforts to restrict accessories — whether extended magazines, noise suppressors or bump stocks — as part of a broader attack on guns themselves.
"It's an effort by [gun control groups] to put points on the board. It's an effort by them to use these horrific tragedies to demonstrate that they're making political progress in their effort to destroy the Second Amendment."