T.J., the 17-year-old grocery boy, sees it all.

He's the one standing outside the Safeway in his blue apron and white shirt, collecting the red plastic shopping carts, helping with the bags. When he's not busy, he stares out over the asphalt.

What he sees is fear.

Some customers tell him he shouldn't be standing there.

Some customers who used to tote their own bags now pull their cars up so he can do it for them.

Some customers recline their car seats while they wait, their eyes wide open.

And some customers scamper through the parking lot as if it were Sniper Alley in Sarajevo, not a humdrum American shopping plaza: They sprint or crouch or fast-walk, head down and zigzagging until they get inside.

"At first, I was wondering 'Why are all these people running?' " he said. "And then I thought, 'Oh yeah.' "

More than two weeks after the first of the sniper shootings, the Washington region tenses for more. The Pan Am Shopping Center in Fairfax County is, in many ways, typical.

It's a hub of the mundane, the kind of place where most Washingtonians do their daily errands: There is a grocery, a drugstore, a McDonalds, a Starbucks, a sports bar and a clutch of other stores.

It looks so normal. But more than the Sept. 11 or anthrax attacks last year, the hidden sniper has injected fear into daily routines, customers and merchants at Pan Am say.

Mike Buterbaugh, the manager of Glory Days Grill, the sports bar, finds himself scanning the forested area across the street. He's looking for the glint of a rifle scope.

Lati Taghavi, the manager of the dance-wear store, says customers now call in and want their items mailed out.

Karen Bartenstein, an administrative assistant at the Long & Foster real estate office, keeps the blinds closed when she's inside; when she's outside having a cigarette, she hides behind a column. After work, she gets her groceries in handfuls instead of all at once so it won't take long to load her car.

"Otherwise, if he's as good a shot as they say he is, I'm an easy target," she said. "We always tell kids that there's no boogeyman. But you know what my niece told me? 'He's the boogeyman.' And she's right. There is a boogeyman."

Not everyone is cowering, of course. In conversations with more than two dozen people at the shopping center late last week, a handful said that they weren't the least bit afraid, or if they were, that their fears were not strong enough to alter their life style.

"I like my odds of being shot: a million to one," said Bruce Barber, 54, a bank executive from Vienna who was having a beer with friends at Glory Days on Thursday night. "If it's your time, it's your time."

But even while talking tough among his softball pals, Barber acknowledged that when he gets off the Metro at Dunn-Loring, he scans the nearby woods for "anything unusual, somebody standing there, or a white van." He said his wife asked him to gas up her car.

Talking to people who are actually at the shopping center doesn't paint the whole picture, though. Many customers simply haven't been showing up. Sales are down, merchants agree, anywhere from "just a little" at the computer store to as much as 70 percent at the Art Stone dance-wear store, which also sells costumes at this time of year. Most stores are seeing declines of about 30 percent.

"I guess there's no Halloween this year," Taghavi sighed amid piles of masks and other holiday apparel. "People are scared enough already."

"People are staying home," said Long Vu, the owner of the nail salon, where business is down 30 percent and most of the chairs were empty Thursday afternoon.

"It's getting close to home," said Gina Sumers, who works at the Ultimate Workout for Women, referring to the shooting Monday night at Seven Corners. "And some of those [customers] coming in, they run in."

Never mind the odds. They run.

In fact, the odds of being the target of a random sniper in the Washington region do seem long, though not as long as winning one of the big lotteries. There are roughly 5 million people, all equally at risk. In one multistate Big Game lottery earlier this year, the chance of picking the correct numbers was one in 76 million.

But as social scientists have noted, people struggle processing the small risk of a major catastrophe. That might explain why some people stroll across the parking lot, others walk fast, and still others run in a zigzag.

At Pam Am, as at shopping centers throughout the region, patrons do their own assessment of the risks. They focus on the forested hill across the street, their proximity to Interstate 66, and the Michaels craft store, a retailer with a location at three of the recent shooting sites. On the plus side, Fairfax police seem to be a constant presence in the Pan Am parking lot.

"Sure, I'm scared," said Alba Chronis of Arlington as she darted back to her car Friday afternoon, stopping occasionally between vehicles to check out her surroundings. "But you have to go on."

"Hey, if it's Lotto, it's one thing," said Robert Macalino, 31, a salesman from Fairfax who was in Glory Days for the Maryland football game Thursday night. "But this is your life."

When Macalino, his brother and a friend arrived in the parking lot, they emerged from their Jetta not just running, but bobbing and weaving.

"I felt most comfortable when I was between two SUVs," Macalino said.

"I was trying to look like I was joking," said the friend, Gail Abrantes, 31, an accountant. "Even though I was kind of scared."

Later, when she suggested walking a few doors down to pick up a few things at the Safeway, her companions quickly talked her out of it. "Usually, it would have been no big deal," Abrantes said.

Maybe more bothersome than feeling scared, many at the shopping plaza said, is the thought that their fear might be exactly what the killer, or killers, intends.

Buterbaugh, the manager of Glory Days, tries to look beyond.

"It's amazing the effect this has had not only on the people directly affected but on general society. It's worse than 9/11. As bad as that was, it happened on one day. Now every time you turn on the TV you hear about proximity to a highway, proximity to a Michaels."

That's why he's scanning the woods for the glare of a scope.

He's also making sure that none of his employees leaves alone, that nervous customers are escorted to their cars, and that no one is forced to wait tables outdoors; instead, he asks for volunteers.

"If anything, you learn to care more about people," Buterbaugh said. "Business will be back. When it's over, everyone will want to get out of their house. I know it."

A tarp was hung along the fence line of the playground at the District's John Eaton Elementary School so that a block party could go ahead as scheduled. Customers shun outdoor tables at Glory Days Grill at Pan Am strip mall. A man heads briskly to his car in front of the Michaels craft store. Smokers take advantage of the pillars in the walkway to find cover.Karen Bartenstein glances through the blinds at her office.