Gun and ammunition sales across the country have risen sharply since Sept. 11 as more Americans take what many consider to be the most personal step toward feeling safer: arming themselves.

According to statistics from the FBI, surveys by firearms associations and anecdotal evidence from storefront gun shops and distributors from Arizona to Florida to Lower Manhattan, the jump in weapons sales quickly followed the first jarring images of the terrorist attacks.

The rise was anywhere from 9 percent to nearly 22 percent during September, October and November, according to FBI statistics on background checks for purchases. The total peaked in October, at 1,029,691.

Those in the gun industry say a range of firearms have been purchased, from high-priced handguns small enough to fit inside a purse to shotguns and assault rifles that can be leaned against a wall inside a clothes closet. And, they say, there has been a steady stream of serious-minded first-time buyers.

"Sept. 11, like other catastrophes, makes people panic, makes them fearful, makes them want to protect themselves and their families against the enemy, who, in this case, is hard to identify," said James Alan Fox, Lipman professor of criminal justice at Northeastern University in Boston.

To many in and out of law enforcement, such a proliferation of deadly weapons is unsettling.

"We are always concerned with the overall numbers of guns that are available and out on the street making things unmanageable for law enforcement," said William Berger, the police chief of North Miami Beach, Fla., who is president of the International Association of Chiefs of Police, the nation's oldest and largest group of law enforcement executives, with 19,000 members worldwide.

Some gun manufacturers — like those in other industries — are aggressively seeking new clients because of Sept. 11. Ithaca Gun Co. is selling its Homeland Security model for "our current time of national need." The Beretta gun company has its "United We Stand," a 9-millimeter pistol bearing a laser-etched American flag. The company sold 2,000 of them to wholesalers in one day in October, said Jeff Reh, vice general manager of Beretta USA.

Gun-control advocates have voiced strong concern about the increased sales, citing statistics showing that guns, though purchased by the law-abiding, often end up later in criminals' hands. Some law enforcement officials echo that thought.

Nevertheless, guns are being bought with the feeling that they will make the buyer safer. Scott Abraham, a Long Island investment broker in his 30s, said he never dreamed of buying a gun until Sept. 11. Last month he bought a Mossberg shotgun because "I don't want to be caught shorthanded," and made a spot to hide it in his house. Thomas M. Iasso, 53, a former police officer who stopped carrying a gun two years ago, bought a .40-caliber Glock after the terrorist attacks — and carries it.

Explaining his purchase, he said, "You can't sit there and tell me you can protect me anymore, because you can't."

According to Andrew M. Molchan, the director of the 4,000-member Professional Gun Retailers Association in Fort Lauderdale, Fla., firearms retailers have seen significant jumps in sales, especially among first-time buyers and the wealthy.

"Maybe they had more to protect or maybe they had more to lose, or, psychologically, they thought they had more to lose," Molchan said.