In an effort to protect the homeless population as temperatures plummeted over the past week, Prince William social services officials have extended the hours of the county's winter homeless shelter and have ventured out to known campsites to encourage people to seek warmth.

County officials said yesterday that they are concerned that homeless people, especially the mentally ill, may resist seeking shelter, exposing themselves to deadly cold on the county's streets and in obscure wooded areas. Some are worried that many homeless people aren't prepared to deal with subzero temperatures and that they often underestimate the amount of heat needed to stay alive.

This week's cold weather has been blamed for at least one death in the region. A shirtless man was found dead in the District yesterday morning. The man was believed to be homeless, and officials said he likely died of exposure.

The county's winter shelter in Woodbridge is now open around-the-clock, offering homeless people a place to warm up during the day in addition to during the center's usual overnight hours. County officials opened the shelter for extended hours as temperatures dipped below freezing this week and plan to keep it open as long as temperatures remain low.

"As long as we are having these lethal temperatures, we will stay open as much as possible," said Debra Danieley, Prince William's director of homeless services.

Danieley said the county's winter shelter has been at capacity--32 filled beds--for quite some time.

Gayle Sanders, director of the Volunteers of America's Homeless Prevention Center in Woodbridge, said that many longtime homeless people in the county will be able to fend for themselves, but that others could be putting themselves in imminent danger without even realizing it.

She said this winter has been especially harsh, considering that last winter was relatively mild and had little snow.

"I wouldn't be surprised if people are found [frozen to death] in campsites or in abandoned cars," Sanders said.

"They may not have the ability to take care of themselves. Without medication and without help, they may not be able to save their own lives."

Another concern for local officials is the rampant use of heating devices in campsites and wooded areas that pose significant fire risks to ramshackle dwellings and tents. Propane heaters and space heaters are of particular concern because of their volatility and proximity to extremely flammable surfaces.

In October 1998, two homeless men were killed in their makeshift campsite on a vacant lot in Manassas after a portable propane heater ignited a plastic tarp, engulfing the area in flames. After the fire, police swept many homeless out of the area.

Social services officials say they are certain those people merely relocated to other parts of the county.

Danieley said she is unsure whether homelessness in Prince William is rising. She said homeless services officials throughout the county are getting a better handle on the population because of recent counts. Last winter, officials identified 309 homeless people--adults and children--in the Prince William area.