Updated

The serial sniper who has been terrorizing the Washington area for the last 10 days may have killed his eighth victim Friday.

A 53-year-old Philadelphia man was shot dead while pumping gas at an Exxon station just south of Fredericksburg in the morning. And while the murder wasn't immediately linked to the recent attacks on nine others, the circumstances -- including the spotting of a white van leaving the area -- were ominously similar.

A state trooper investigating an accident across the street on Friday heard the shot and saw the victim fall, but the gunman vanished into the gray drizzle.

"Obviously we're dealing with an individual who is extremely violent and doesn't care," Spotsylvania County Sheriff's Maj. Howard Smith said.

Authorities did not immediately confirm the shooting was the eighth slaying committed by the sniper over the past 10 days. Like the other attacks, witnesses described a single shot, fired apparently at random at someone going about his everyday activities.

"The shooting certainly looks similar," said Montgomery County (Md.) Police Chief Charles Moose, who sent investigators to the scene.

Added Smith: "Any time we get a shooting right now we're going to treat it as if it is connected to this case until it's proven differently."

Analysis of ballistic evidence from the scene was not expected until Saturday, though a spokeswoman for Gov. Mark R. Warner said more bullet fragments were recovered here than from the other attacks.

Citing witness reports of a white van carrying two people, authorities immediately blocked traffic on nearby highways and checked vehicles. The roadblocks turned stretches of Interstate 95 into a virtual parking lot, backing up traffic for miles on the eve of the Columbus Day holiday weekend.

Col. W. Gerald Massengill, superintendent of Virginia State Police, cautioned the public not to focus only on white vans.

"We don't want preconceived notions out there, but certainly you have to play the hand that you're dealt and the information that has come to us is white vans," Massengill said.

Bruce Bingham, who works at a gas station across from the Exxon station where the shooting happened, said he heard a single shot and saw an unmarked white van driving away from an intersection. Bingham said the light turned green right after the shot and he speculated that someone in the van might have timed the shooting to coincide with the light.

The victim's name was not released as authorities were still trying to locate his kin.

The sniper has killed seven people and wounded two, firing from a distance with a high-powered rifle at people going about activities as mundane as mowing the lawn, shopping or strolling down the street.

White House spokesman Ari Fleischer said the near-daily shootings have become part of President Bush's regular FBI briefing.

Asked if the attacks could be connected to a terrorist group, Fleischer said: "We don't know it is or is not. Whatever the word you want to use to describe it, this is clearly terrorizing the people who are involved, and their families."

Moose said a special FBI unit had not yet finished a graphic aid for the public to help in the search. He did not say what it would show.

A toll-free hot line -- 888-324-9800 -- set up to accept tips was overwhelmed by calls Friday. Police were advising callers getting busy signals to keep calling. Additional phone lines were being installed.

Across metropolitan Washington -- an area of some 5 million people -- Friday night football games at area high schools were canceled along with other outdoor activities.

Many were fearful and jittery. Tipsters overwhelmed the 911 center in Montgomery County. Police were called to an elementary school in Bowie, Md., after receiving a report of shots fired; it was apparently firecrackers. A parent, Elaine Henry, described the scene out the school as "near chaos. Parents were everywhere trying to get their children."

At a restaurant near the site of Friday's shooting, Rebecca Didion parked her car illegally against the curb to avoid walking across a parking lot and making herself a better target.

She said she kept her four children out of school and the words they are telling her have become increasingly desperate: "My 8-year-old said to me: 'If it's our time to go, it's our time to go, so why can't we just go on with our lives?"'

Massengill said the ability to track down leads has improved substantially in the past week as various law enforcement agencies closed ranks. But he sounded frustrated, telling reporters: "I'm not going to sit here and display a lot of confidence."

At a gas station in Gaithersburg, Md., co-owner Paul Thomas said he is aware that his station fits some of the characteristics of the other shootings: near big roads and highway ramps.

"We know we fit the profile," he said. "We've got people here 24 hours a day, so I've got the problem 24 hours a day."

Ed Penny pulled his lemon-yellow sports car off the clogged interstate into a northern Virginia Texaco Mini-Mart to fuel up just hours after Friday's attack, saying he refused to let the shootings change his daily routine.

"I can't let it harp on my feelings. I can't let it make me scared of stopping for gas," Penny said. "He's just one person, and he's a psycho."

The Associated Press contributed to this report.