GAFFNEY, S.C. - Terrified residents canceled Fourth of July plans and holed up in their homes yesterday as investigators hunted a serial killer believed to have shot four people to death.

Tanya Phillips had been looking forward to a backyard barbecue at her brother's house but instead planned to stay home with her doors locked.

"I'm not taking any chances," said Phillips, 32, a mother of two who works in a day-care center. "I'll go out during the day, but not at night. I just don't feel safe."

Plenty of evidence links the killings, though officials have not yet determined how the victims are connected or whether they knew the killer, said Cherokee County Sheriff Bill Blanton.

"Yes, we have a serial killer," he said at a news conference in this rural community 50 miles south of Charlotte, N.C.

So far, all investigators have to go on is a sketch of a suspect and a description of a possible getaway vehicle, though police would not say who provided that information.

The latest victim, Stephen Tyler, 45, was found shot to death in his family's small furniture and appliance shop near downtown Gaffney around closing time Thursday. His 15-year-old daughter was seriously injured. Tyler's wife, his older daughter, and an employee found them in Tyler Home Center, county coroner Dennis Fowler said.

A day earlier and about seven miles away, family members found the bodies of Hazel Linder, 83, and her 50-year-old daughter, Gena Linder Parker, bound and shot in Linder's home. Blanton would not say whether Tyler and his daughter were bound.

The killings began last Saturday about 10 miles from Tyler Home Center, where peach farmer Kline Cash, 63, was found shot in his living room. Blanton said the killer may have first spoken with Cash's wife about buying hay. She left and came home a few hours later to find her husband's body. Investigators said it appeared he was robbed, but they have not determined if anything was taken in the other killings.

Cherokee County, home to about 54,000 people, had just six homicides in all of 2008, and half that the year before.

Residents have "their guard up and their gun handy," said State Sen. Harvey Peeler. He recalled that the area was terrorized once before, in the 1960s, by a serial killer dubbed the Gaffney Strangler.

Otherwise, Gaffney is known for a giant water tank shaped like a peach that can be seen from Interstate 85.

The sheriff reminded people that they have a right to protect themselves and advised salespeople and others to avoid knocking on strangers' doors. "People are going to start shooting at shadows," Blanton said.