Prince William County lawmakers moved yesterday to revamp parts of the county's troubled fire and rescue service, acting one week after a Dale City man died of a heart attack after a 32-minute wait for a volunteer ambulance crew.

The Board of County Supervisors, in a series of changes negotiated with the powerful volunteer chiefs who control Prince William's fire and rescue service, voted to stagger the shifts of the paid personnel who supplement the volunteers to close the "windows of vulnerability" that exist during morning and evening rush hours.

The supervisors and fire chiefs also agreed to create a commission to study the future of Prince William's fire and rescue service, which has remained in the hands of volunteers while increasingly sophisticated medical equipment and the county's soaring population have imposed new demands on the system.

"There will be more headlines if we don't get this resolved in the very near future," said Supervisor Edwin C. King (D-Dumfries).

King was alluding to newspaper articles last week about James Overman, a 47-year-old federal worker who died after four volunteer rescue squads did not respond to calls from dispatchers after 6 a.m. Feb. 23. The two crews that did respond were not qualified to use advanced life-support equipment such as defibrillators and heart monitors.

Overman arrived at Potomac Hospital, about four miles from his home, nearly one hour after an ambulance request was placed with Prince William's 911 emergency number. He was declared dead a short time later.

Starting next week, four advanced life-support units staffed by county employees will be on duty between 5 and 7 during the morning and evening. Currently, professional staffers work 7 a.m. to 5 p.m. on weekdays, with volunteers manning the system at all other times.

Volunteers, only a small number of whom are trained to provide advanced life support, will continue to be responsible for the system from 7 p.m. to 5 a.m.

County officials said the schedule changes may be only the first of several changes in the fire and rescue service prompted by Overman's death. The 17-member commission created yesterday, which will include volunteers and county government representatives, will examine the entire relationship between the volunteers and the county government, with an aim toward improving the often-hostile relations between the two, and redefining which group should be responsible for which service.

William Spicer Jr., the chief of eastern Prince William's Occoquan-Woodbridge-Lorton fire company, said yesterday that, ideally, all advanced life-support service should be provided by paid county staff members.

"We can't guarantee {such} service on a 24-hour basis," said Brian Hickerson, who heads Prince William's volunteer chiefs association, adding that learning to use advanced life-support equipment has become too difficult.

Hickerson said the fire chiefs would like to cede full responsibility for advanced life support to the county within 18 months. But, he and other officials said, it remains uncertain whether Prince William could afford to take over the service by then.

The volunteers will likely be less willing to hand over responsibility in other areas.

County Executive Robert S. Noe Jr. has proposed a uniform countywide tax to finance fire and rescue service, in place of the widely varying levies now collected separately in each of Prince William's 13 fire districts. The volunteers have promised to fight this initiative vigorously. The chiefs now control their own budgets, but would lose part of that responsibility under Noe's proposal, and they fear this would erode the volunteers' independence.

In another action, the supervisors voted to create a position to coordinate relations between Noe and the volunteers. The county already has a similar position, but some volunteers have said they hold Selby Jacobs, the county's director of fire and rescue operations, in disdain.