After a Glock-wielding gunman killed six people at a Tucson shopping center on Jan. 8, Greg Wolff, the owner of two Arizona gun shops, told his manager to get ready for a stampede of new customers.

Wolff was right. Instead of hurting sales, the massacre had the $499 semiautomatic pistols - popular with police, sport shooters and gangsters - flying out the doors of his Glockmeister stores in Mesa and Phoenix.

"We're at double our volume over what we usually do," Wolff said two days after the shooting spree.

A national debate over weaknesses in state and federal gun laws stirred by the shooting has stoked fears among gun buyers that stiffer restrictions may be coming from Congress, gun dealers say. The result is that a deadly demonstration of the weapon's power has boosted sales of handguns in Arizona and other states, according to federal law enforcement data.

"When something like this happens, people get worried that the government is going to ban stuff," Wolff said.

Arizona gun dealers say that among the biggest sellers over the past two days is the Glock 19 made by privately held Glock GmbH, based in Deutsch-Wagram, Austria. It is the model used in the shooting.

One-day sales of handguns in Arizona jumped 60 percent on Jan. 10 compared with the corresponding Monday a year ago, the second-biggest increase in any state in the country, according to FBI data. From a year earlier, handgun sales ticked up Tuesday 65 percent in Ohio, 16 percent in California, 38 percent in Illinois and 33 percent in New York, the FBI data show, and increased nationally about 5 percent.

Federally tracked gun sales, which are drawn from sales in gun stores that require a federal background check, also jumped after the 2007 massacre at Virginia Tech, in which 32 people were killed.

"Whenever there is a huge event, especially when it's close to home, people do tend to run out and buy something to protect their family," said Don Gallardo, a manager at Arizona Shooter's World in Phoenix, who said that the number of people signing up for the store's concealed-weapons class doubled over the weekend. Gallardo said he expects gun sales to climb steadily throughout the week.

Jared Lee Loughner, the 22-year-old accused in the shooting, had a petty criminal record, yet so far there's no evidence that his background contained anything that would have prevented him from buying a gun in Arizona.

Critics have focused on the extended magazine used in the shooting. It was illegal until 2004 under the expired federal ban on assault weapons. The clip - still banned in some states and popular in Arizona, gun dealers say - allegedly allowed Loughner to fire 33 rounds without reloading.

Democratic Rep. Carolyn McCarthy of New York said this week that she plans to introduce legislation that would ban the high-capacity magazine.

"The fact that the guy had a magazine that could carry 33 rounds - he was not out to just kill. He was there to do a mass killing," said Dr. Lawrence Kobilinsky, a forensics expert at John Jay College of Criminal Justice in New York.

Wolff called the shooting "horrible." Nonetheless, it has created a surge of publicity for the gun, he said.

"It's in the news now. I'm sure the Green Bay Packers are selling all kinds of jerseys today as well," he said.