The numbers of homeless people in Prince William County have soared in recent years as the county's dramatic growth has pushed the price of housing beyond the reach of many residents and has forced some to spend nights in tents and cars, social service officials said yesterday.

Each night, nearly 60 people sleep in three shelters run in conjunction with Prince William's Department of Social Services or in shelters run by church groups, according to county social workers.

At the same time, they said, an estimated 150 people are living temporarily with neighbors or friends or are on the streets.

A few years ago, homelessness was virtually nonexistent in the county, but shelters now turn away people on a daily basis -- a problem that will require a rising share of public money to solve, said Ricardo Perez, the county's director of social services.

The Prince William Board of County Supervisors, after a presentation by Perez yesterday, appointed a task force to study the issue of homelessness and approved spending $65,000 to help homeless people and residents facing imminent eviction.

The homeless problem in Prince William -- Northern Virginia's second largest locality, with more than 200,000 people -- is mild in comparison with the District and other heavily urbanized areas. But it stands in contrast with the image of affluence popularly associated with Northern Virginia's high-growth suburbs.

Prince William's homeless "are not standing around on corners," said Perez. "The homeless are not as noticeable in our county as they are in urban areas."

Many of Prince William's homeless are longtime residents who have been squeezed by rising apartment rents or are newcomers who were lured to Northern Virginia by the healthy economy but have trouble supporting themselves in part-time or low-income jobs, officials said.

"We have plenty of jobs, but what we don't have is housing," said Sarah Anderson, who runs a shelter supported in part by county funds in Dumfries, along eastern Prince William's Rte. 1 corridor.

Prince William's homeless figures mirror those of other suburban localities. In Fairfax County, for example, the number of people using county shelters has more than doubled since 1985, to almost 2,800 last year, said Verdia L. Haywood, the deputy county executive for human services.

Haywood said that the county's five shelters, with 262 beds, are owned by the county, and that most of their operation is paid for with tax dollars.

In Prince William, by contrast, the government is straining to meet the costs of rapid growth and must rely more heavily on partnerships with community groups to provide help for the homeless, said Perez.

Cutbacks in federal funding have meant that virtually no low-income housing has been built in Prince William in recent years, exacerbating the problems of homelessness, he said.

Anderson said that about a third of Prince William's homeless have psychiatric or substance abuse problems, about a third hold jobs not lucrative enough to meet rent costs, and about a third are on some form of welfare. Many are in families headed by single parents, she said.