The large-scale federal, state and local investigation into the serial sniper who has terrorized the Washington suburbs widened last night to Manassas, Va., where a man was shot to death at a gas station.

Montgomery County police headed to the site at Battlefield Sunoco, where the man was reported to have been fueling his car when he was hit, apparently by a single shot.

With the investigation in its seventh day, the police were analyzing a few scant clues -- including a mysterious note that suggests the killer is taunting the detectives on his trail.

Frustrated by not only the fruitless search for the killer but also several days of intense news media attention, Montgomery County Police Chief Charles Moose angrily criticized reporters yesterday for disclosing the note's discovery.

Investigators say the note was found in woods near Benjamin Tasker Middle School, where the sniper shot and critically wounded a 13-year-old boy heading into school Monday morning. The message, scribbled on a tarot card known as the Death card, read, "Dear Policeman, I am God."

Moose said the leak about the card to a Washington television station Tuesday night might have a "detrimental" effect on the investigation, which now involves nearly 200 investigators from several states and the federal government.

"This is an adjustment that we feel is unwarranted because we should have been able to control it," Moose said.

It is unclear what police have gleaned from the card or its significance to the gunman. Police discovered the tarot card next to a shell casing from a high-powered rifle in an area of flattened grass with a clear line of sight to the front of the school, law enforcement officials said.

Officials of the federal Bureau of Alcohol, Tobacco and Firearms said the shell casing found next to the tarot card was .223-caliber, the same as in all the other shootings. They declined to discuss other forensic evidence in the case.

The scene suggests the sniper had been lying in wait for a victim, perhaps arriving under cover of darkness and staying hidden for several hours before the attack, officials said.

In the other shootings, police say the gunman might have been stationed in a car or truck, or quickly taking aim from a hidden vantage point. After firing a single bullet in each case at someone doing a routine activity -- pumping gas, mowing a lawn, vacuuming a car -- he packed up his gear and fled.

Four people were killed on the morning of Oct. 3 in Montgomery County; another was slain that night in Northwest Washington. The sixth victim had been killed Oct. 2 outside a Wheaton grocery store.

Last night's shooting occurred about 8:15 p.m. at a gas station on Sudley Road, a short distance from Interstate 66 and about 30 miles west of Washington. Although police could not say with certainty it was related to the series of sniper killings, the similarities were enough to bring detectives from Maryland to the scene.

Virginia State Police said two males were seen driving away in a white vehicle after the Manassas shooting.

Prince William County police spokeswoman Sgt. Kim Chinn said one man was killed, but she had few other details. She said police did not know where the shots came from or how many were fired.

Police had blocked off several streets around the gas station and were interviewing people at the scene.

"We are still very preliminarily beginning this investigation," Chinn said. "We have been in contact with the officials from Maryland and the task force there, so we are sharing any information we have."

Thus far, two people have survived the attacks: a woman shot outside a Michaels craft store in Fredericksburg, Va., Friday afternoon; and the 13-year-old, who, despite a critical injury that damaged several of his organs, is recovering.

Yesterday, the boy got a special get-well wish: a video and autographed jersey from Orlando Magic forward Tracy McGrady. The boy had told his doctors and nurses that he was a McGrady fan.

"That's really touching," McGrady told The Orlando Sentinel. "It was real touching to me that of all the guys in this league -- Shaq [O'Neal], Kobe [Bryant], Michael Jordan -- he called my name."

Police released few details about the crimes on a day that was eerily calm. Detectives continued yesterday to receive hundreds of tips, including one that led to the search of a wooded area near Friendly High School in Fort Washington, Prince George's County.

Officers searched the woods of the high school after a tipster reported seeing a man enter the trees carrying a satchel large enough to contain a rifle, authorities said.

But police found nothing, saying the man might have been part of a surveying team that had been reported in the woods the day before. Police also detained a driver but released her after questioning.

Montgomery County police also went to a house on Summit Avenue in Kensington for reports of a man shooting a gun in his house. Police took the man into custody as he was walking out his front door and obtained a warrant to search the house, which police said was damaged by bullet holes and had weapons in it.

Police released no other details and said they were investigating the incident.

Moose and other officials urged people to call with tips, saying a casual observation of something suspicious might prove to be the break detectives desperately need.

While requesting continued help, Moose also lashed out at those he believes are hindering his investigation.

He strongly criticized former FBI profilers who have been omnipresent commentators on television and in other media reports, saying they might prevent people from calling in tips because they do not think suspicious activity fits with experts' opinions of the shooter.

"Unfortunately, we have any number of talking heads in the media, retired police professionals -- and you know, as a police professional, it is very insulting when they are retired police professional because we know that they have not been briefed. They have not seen the evidence. They've not talked to any investigators."

"And so it's all fun to be on television, but maybe they need to come here, live here, sit outside and have coffee and then let's see how open they'll be to ranting and raving and call the suspect or the suspects names," Moose said.

Moose also questioned why Gov. Parris N. Glendening and Washington Mayor Anthony A. Williams, who both stood next to the police chief during a nationally televised news conference, would call the sniper a "coward."

"The governor was talking about his emotions," Moose said during a press briefing. "The governor's training is not in the law enforcement field. I am convinced that the governor will never do that again."

The investigation has seen dozens of detectives offer their help, with several federal agencies, including the FBI and ATF, assisting Montgomery County police, who remain the lead investigative agency.

U.S. Attorney General John Ashcroft said federal authorities have not taken over the investigation, partly because they believe the killer will face more stringent death penalty guidelines under Maryland state law.

Experts say an investigation as large as the one unfolding in the Washington suburbs is daunting because of the sheer number of people involved.

"There are always logistical problems like that when you bring large number of [investigators] into a particular area," said Daniel Mihalko, a U.S. postal inspector who worked on the Unabomber case.

"You have to find people apartments. You've got to make sure they're equipped with vehicles and radios that they can talk to each other with."

"That's always a logistical problem. ... There's just a whole lot of coordinating to make sure you're working effectively."

He added, "The toughest thing is whenever you gather information you need to have a system in place to make sure every piece of information is evaluated. Somebody has to be looking at the big picture."

Sun staff writer M. Dion Thompson and the Associated Press contributed to this article.