The reminder could not have been more sobering.

"You are at Ground Zero," said FBI Special Agent Jim Rice, capturing the attention of Northern Virginia police and fire officials clustered around him. "A bomb going off in your neighborhood is just as effective in a terrorist's mind as one on Pennsylvania Avenue."

The message was real yesterday even if the scenarios were not at a day-long seminar at George Mason University in which local officials pondered how to prepare for a terrorist attack on the region and its potentially cataclysmic aftermath.

The fictional crises included an anthrax attack on Alexandria that began in a small potted plant in an office building and within days had killed more than 400 people, spreading fear and confusion. Months later, the death toll continued to climb.

The seminar, sponsored by the American Society for Public Administration, wasn't the first time local police and fire chiefs have tried to plan for domestic disaster. The Metropolitan Washington Council of Governments established a medical strike team of paramedics, firefighters and police officers in 1996 that stands ready to wade into a chemical or biological incident, maintaining a large cache of drugs and equipment in Arlington County.

But gaps remain, not only in the emergency response to a crisis such as the release of sarin gas in the Tokyo subway in 1995, but in the treatment and developments that follow in the months afterward.

As the officials broke into small groups yesterday, they analyzed difficulties such as how jurisdictions would communicate with one another and whether local hospitals could handle large numbers of casualties.

"I think we have a huge infrastructure problem," said Arlington Fire Chief Edward Plaugher. "If you get more than a couple of victims, you're in trouble. Where do you get 50, or 500, extra beds?"

The federal Centers for Disease Control maintains a stockpile of drugs in the event of critical need, Plaugher said, but there's no plan in place to distribute them on short notice.

Plaugher said he had repeatedly tried to interest health care officials in attending similar meetings, without success. Health care representatives were not invited to yesterday's seminar.

Fairfax City Police Chief M. Douglas Scott said that when different fire and police departments need to talk to each other, trouble is likely. Separate types of equipment and different frequencies are bound to cause confusion unless worked out in advance, he said.

And though chemical warfare may cross state lines, police and fire officials often are reluctant to do so, especially with the threat of lawsuits looming, Vienna Police Chief Daniel V. Boring said.

The discussions weren't purely theoretical. The FBI's Rice, head of the bureau's National Capital Response Squad, said his agents had recovered seven radioactive packages in the last 45 days. Most were low-level medical waste or mailings from contaminated sites, he said, but the team treated each one seriously.

"Everything is real until we prove it's not," he said.

At the end of the day, the seminar's recommendations were presented to officials from the Justice Department's Office of State and Local Domestic Preparedness Support, and Virginia's Department of Emergency Services.

Virginia is holding two similar meetings in coming weeks, and assistant state coordinator George W. Foresman said the recommendations are "going to serve as a foundation for much of what we do from this point forward."