The death of a Prince William County man has focused new attention on a fire and rescue service that is largely outside the authority of the county government, and is controlled instead by volunteers under a system established during the county's days as a rural outpost, county officials said yesterday.

James Overman, a 47-year-old federal worker who suffered a heart attack early Tuesday morning, waited 32 minutes for an ambulance and was declared dead shortly after he arrived at Potomac Hospital, nearly one hour after a call was placed to the county's emergency 911 number.

Four volunteer rescue squads failed to respond to county dispatchers shortly after 6 a.m., and the two teams that did arrive were not trained to use special life-saving equipment. The county's average response time is six to 10 minutes, according to the medical director of the county's eastern half.

The incident has spotlighted the blurred lines of accountability in Prince William's fire and rescue system. Though the service is dominated by volunteers, the legal liability rests with the county government and taxpayers.

The slow response, roundly criticized by Prince William officials yesterday, may give new impetus to proposals to revise the fire and rescue service -- a collection of 12 mostly autonomous companies headed by volunteer chiefs who historically have been hostile to suggestions that would transfer control to the county.

The Board of County Supervisors has no say in the hiring or firing of the 12 volunteer chiefs, who are elected by the volunteers.

"It's been up to the volunteers to determine the level of service, and their word has generally prevailed," said County Executive Robert S. Noe Jr., who promised to investigate Tuesday's incident but cautioned that the volunteers are outside his domain.

Still, some officials feel the event may spur changes in the fire and rescue system.

"As regretful as the event has been, it is no doubt an event which will lead to very early improvements," said Supervisor Edwin C. King (D-Dumfries).

Other members of the county board joined King in calling for staggering the work schedules of the professional firefighters who supplement the volunteers to eliminate the service's "windows of vulnerability" -- when the paid staff is absent and the volunteer force is thinly staffed.

The most vulnerable periods are from 5 to 7 during morning and evening rush hours. Overman's call came at 6:07 a.m.

Prince William is served by 109 paid, nonadministrative fire and rescue personnel and about 700 volunteers. The 12 fire companies devise their own budgets, which are financed by levies collected by the county.

Historically, Prince William's fire volunteers have been a politically influential group that elected officials are reluctant to criticize.

Many volunteers reacted unfavorably to a proposal Noe made this year that would bring the fire system's finances more tightly under county control. Noe wants to make the fire levies paid by residents, which now vary widely among Prince William's 13 fire districts, uniform throughout the county.

The hybrid nature of Prince William's fire system is particularly evident during emergencies, when the county's paid personnel take their orders from volunteer chiefs.

Noe and other officials praised the volunteer force yesterday as a generally hard-working and dedicated group that has served the county well in years past. Noe said the volunteers will continue to play a principal role, if for no other reason than that the financially strapped county can ill afford the "staggering" cost of a fully professional service.

However, Prince William's speedy growth has imposed new demands on fire service that will inevitably require broader county involvement, officials said. Without clearer accountability, they said, there is no way the system can evolve to meet the needs of a changing community.

"The demands being made on a thinly manned volunteer system are beginning to break down the system," said King, adding that he believes changes can be implemented while preserving the volunteer character of Prince William's force.

"The time has come to do something about" the system's weak links, agreed Supervisor John D. Jenkins (D-Neabsco). "And I think the citizens are willing to pay for it."

Professionals must play a greater role in the fire service, officials said, partly because finding qualified volunteers has become increasingly difficult. Most of Prince William's newer residents have little time or inclination to devote time to fight fires and learn to use increasingly sophisticated life-saving equipment.