Tom McChesney became concerned when four youths followed him out of a grocery store and began shouting insults at him.

McChesney managed to get inside his van, but the problem only got worse. Soon the youths were slamming shopping carts against his vehicle.Worried, McChesney pulled out his secret weapon: a cellular phone.

Within moments a police car zoomed into the parking lot and two of the teenagers were caught.

The phone "gives me a great sense of security," said McChesney, 34, a contractor who bought the phone to stay in touch with customers. "It's a good tool to have - probably safer than a gun."

Like McChesney, hundreds of cellular phone owners in the Tampa Bay area are finding that the phones are not just business tools. They also can be a lifesaving aid in an emergency. Car phone users have found hit-and-run suspects, reported hundreds of traffic accidents and helped police catch drunken drivers.

Calls from cellular phones to 911 emergency centers have gone up 60 percent to 100 percent since a year ago, emergency dispatchers said. Hillsborough County, for example, gets 70 to 80 cellular calls to 911 every day - about 5 percent of its total calls. Nationally, someone makes a cellular call to a police or fire department every 11 seconds, according to the Washington-based Cellular Telecommunications Industry Association.

"It's made it easier to be a good Samaritan," said David Bilodeau, Pinellas County's director of emergency communications. "From an air-conditioned car, it's so easy to dial 911, report an accident and keep on going."

Bilodeau should know. During his commute home one day last month, he reported three accidents from his mobile phone.