MANASSAS, Va.

-- A man was gunned down moments after filling his tank at a Virginia gas station, the latest deadly turn in the investigation of a sniper who is stalking the Washington area.

Police said they didn't know if the Virginia slaying was linked to the other attacks, but the shooting only heightened fear that the sniper had struck again.

The man was shot Wednesday night in Prince William County, near Manassas, approximately 30 miles west of the nation's capital and 43 miles from Bowie, Md., the site of Monday's shooting that wounded a boy outside a school.

Virginia State Police said two men were seen driving away in a white minivan after the shooting. The victim, who was traveling alone and not from the area, had just finished paying for gas when he was shot, Prince William County police chief Charlie Deane said early today.

The shooting came one week after the first of six sniper slayings in Washington, Maryland and Virginia. Two other people have been wounded. The woman wounded in Virginia last week was released from the hospital Tuesday. The wounded schoolboy, whom police have not identified, remained in critical but stable condition today.

A tarot card with the words ''Dear policeman, I am God'' was found near a shell casing outside the school in Bowie, a source familiar with the investigation said on the condition of anonymity.

Maryland investigators went to the scene of Wednesday's killing because of similarities with the previous shootings, and Virginia police were sharing information with them.

''We are certainly working the case with that (a possible link) in mind,'' Montgomery County Police Chief Charles Moose said this morning.

A Maryland witness told police he saw two men in a white truck or van leaving the scene of an earlier shooting outside a post office. Two of the Maryland shootings were at gas stations.

''Everything is very similar,'' Montgomery County Executive Douglas Duncan said. ''Let's hope this is not it.''

The shell recovered in Monday's school shooting was a .223-caliber, the same kind of bullet that authorities believe was used in the earlier shootings. It was the first casing found since the slayings began Oct. 2.

Michael Bouchard, an agent with the federal Bureau of Alcohol, Tobacco and Firearms, would not say whether authorities had linked the casing to the attacks.

Moose wouldn't comment Wednesday when asked about the tarot card, and angrily suggested unapproved information had been leaked.

''I need to make sure I don't do anything to hinder our ability to bring this person or these people into custody,'' Moose said.

Investigators say the sniper, or snipers, fired from a distance with a high-powered hunting or military-style rifle. All the earlier victims had been felled by a single bullet; Moose wouldn't comment today on whether the Manassas victim also was killed that way.

The ''I am God'' message left on the tarot card called the Death card was first reported by WUSA-TV and then by The Washington Post. Police sources told the newspaper the items were found 150 yards from the school in a wooded area on matted grass, suggesting the gunman had lain in wait.

The Post reported today that the tarot card also contained a handwritten request from the sniper that it not be revealed to the media. Some detectives had hoped that if they honored the request, the sniper might communicate with investigators again, the newspaper quoted sources as saying.

Tarot cards, used mainly for fortunetelling, are believed to have been introduced into western Europe by Gypsies in the 15th century. Many tarot enthusiasts say the Death card usually does not connote physical death, but instead portrays a symbolic change or transformation.

Crime experts, while noting that the link between the card and the sniper remained unconfirmed, recalled other serial killers who left ''calling cards.''

One of the most notorious was David Berkowitz, who killed six people in New York in 1976-77. He wrote a letter to newspaper columnist Jimmy Breslin and left a note addressed to a police detective that said: ''I am a monster. I am the 'Son of Sam.'''

Robert K. Ressler, a former FBI profiler, interviewed Berkowitz after his arrest.

''He said this was a stimulating thing for him to see the letters in the paper,'' Ressler said. ''Even though he's the only one who knows, notoriety becomes very satisfying to an inadequate loser. It's a way of imposing power and control over society.''