Alarmed by an increase in the use of illegal fireworks, Northern Virginia fire officials have launched an effort to inform the public about fireworks safety and have put in place an aggressive enforcement plan for the Fourth of July.

At a news conference, fire marshals from six counties and cities and Fort Belvoir said many of the fireworks lighted on July 4 are illegal and can lead to fires. On hand were officials from Arlington, Fairfax, Loudoun and Prince William counties, the cities of Fairfax and Manassas and the Army post. They showed examples of banned fireworks, some of which can be bought on the Internet.

The officials said they will step up patrols in their jurisdictions to confiscate illegal fireworks but asked residents to help them by reporting the use of banned fireworks to the fire department.

"It's safe to say that there are probably just a few residential areas in Northern Virginia where you weren't able to either hear or see illegal fireworks discharged last Fourth of July," Prince William Assistant Fire Chief Kevin McGee said at the news conference. "These discharges have been [at] backyard parties, neighborhood displays and individuals' use of illegal fireworks," McGee said.

Last year Prince William fire officials confiscated more than $10,000 worth of illegal fireworks on July 4, a fraction of the amount authorities said were discharged that night.

"We found that many of the citizens that we approached last year expressed surprise when we confiscated their illegal fireworks," McGee said. "They felt that they purchased those fireworks legally and that their possession was legal."

Julie L. Heckman, executive director of the American Pyrotechnics Association, an industry group, said at the news conference that Virginia allows a variety of fireworks regulated by the federal Consumer Product Safety Commission. Legal devices in Virginia include cones, sparklers, sparkling devices and novelties. Illegal fireworks include Roman candles, skyrockets, aerial shells with mortars, and firecrackers.

Bottle rockets -- the whistling, sparkling fireworks that shoot into the air, often turning a backyard display into an ersatz professional show -- are the illegal devices most commonly used each Independence Day.

"The problem is that you have no control over where it goes," Capt. Tim Taylor, a Prince William fire and rescue spokesman, said in an interview.

Heckman said the use of fireworks in the United States has risen from 67 million pounds in 1990 to more than 236 million pounds in 2004.

With that, the risk of fires set by fireworks has increased as well.

Last July, a family of three was burned out of a Woodbridge home after an illegal bottle rocket set shrubs ablaze and the fire quickly spread to the house. Also that month, fireworks lodged into the siding of an apartment building in Manassas, causing a smaller, less destructive fire.

In March, a Forest Park High School football player died of injuries he suffered after a bag of illegal fireworks ignited in a car in which he was riding.

The events prompted an unprecedented effort by Prince William fire officials to start a public education and enforcement effort, which other jurisdictions have joined.

"We decided that it was time just based on those three incidents," said Taylor. "In the past, we have not advertised the fact that most fireworks are illegal in Northern Virginia."

The Prince William County Fire and Rescue Department has sent out mailings explaining that fireworks must be purchased from authorized vendors who sell fireworks approved by Northern Virginia fire marshals. About 70,000 fliers were placed in the water and sewer bills of Prince William County Service Authority customers, and thousands more were handed out at offices of the Northern Virginia Electric Cooperative and at a Potomac Nationals game, Taylor said. Information was also placed in a county government newsletter that goes to 125,000 households.

In addition to the public education campaign about safety, Prince William has established an amnesty period when residents can turn in illegal fireworks for destruction. Residents often do not know what to do with unused fireworks, especially illegal ones, Taylor said. On the Fourth of July weekend, about 20 fire marshals and police officers will patrol the county looking for illegal fireworks, which will be confiscated, Taylor said.

Fire marshals are encouraging people to attend professionally supervised displays, either on the Mall in downtown Washington or at a number of shows at parks and stadiums in the region.

A list of those displays will appear in next week's Extra.

Capt. David M. McKernan, left, deputy fire chief in Fairfax County, answers questions at last week's news conference while Fairfax City's Capt. Keith Cunningham examines an array of fireworks. Fairfax City Life Safety Officer Edward Clark, right, lights a type of fireworks that is legal in Northern Virginia. Legal devices include cones and sparklers. Many people don't realize common devices such as firecrackers, above, are illegal, say officials.