Updated

Fear gripped Cherokee County, S.C., this Independence Day weekend as a teenage girl died at the hands of what police say is a serial killer.

Five people have been shot dead — some bound before dying — in the past week in the largely rural county southwest of Charlotte, N.C.

Fourth of July celebrations were canceled, residents armed themselves and Sheriff Bill Blanton advised traveling salesmen not to knock on doors and asked people who broke down on roads not to ask locals for help because "people are going to start shooting at shadows."

"Every tip that comes in, we are sending out investigators and following any lead," Gaffney Police Chief Rick Turner said at a news conference Saturday.

Abby Tyler, 15, died Saturday in a Spartanburg, S.C., hospital after fighting for her life for nearly two days. She and her father, Stephen Tyler, 48, were both shot Thursday evening as they closed the family store in Gaffney, S.C. Abby's mother and sister found her wounded and her father dead.

On Wednesday, relatives found 83-year-old Hazel Linder and her 50-year-old daughter, Gena Linder Parker, bound and shot to death at Linder's home.

The killing spree began a week ago Saturday when the wife of 63-year-old peach farmer Kline Cash found him dead in their home.

Blanton said Thursday that the killer appears to have first spoken with Cash's wife about buying hay in a ruse to commit the crime. She left and then came home a few hours later to find her husband's body.

"We think she may have been his intended victim," the sheriff said.

Authorities had no explanation for the apparently random nature of the slayings.

"There's no evidence there is a hit list," Blanton said Friday. "There's no evidence he knows the victims. There's no evidence the victims are connected [to each other]."

The shootings all occurred within about 10 miles of each other.

The Tyler family's pastor at Cherokee Avenue Baptist Church in Gaffney prepared a Sunday sermon for the slain father and daughter, as well as the wife and sister they left behind.

"As Christians, we don't live by explanations. We live by promises. We live by faith, not sight," Pastor Clyde Thomas told the Spartanburg Herald-Journal Saturday, even as he admitted he had a pistol with him in his office.

Police set up checkpoints throughout the county and stopped any vehicle that looked remotely like the silver 1991 to 1994 Ford Explorer that authorities believe the killer is driving.

Hundreds of officers are on the case, working as hard as they can even though they are physically drained, Turner said.

"Some have been out here for well over 24, 48 hours maybe even longer than that with very little cat naps here and there," Turner said.

Dozens of local, state and federal investigators were assigned to the case when the first three killings were linked Wednesday. But a day later, the fourth and fifth killings happened less than half a mile from the sheriff's office serving as the headquarters for the investigation.

"We're knee-deep in the investigation," Blanton said Sunday. "There's fear and concern here and there should be concern."

Investigators have released a sketch of the suspect, saying he is in his 40s, with salt and pepper hair, about 6-foot-2, and roughly 200 pounds.

Officials in Cherokee County, best known for the giant water tower painted like a peach along Interstate 85, asked people to pray for the families who have lost loved ones and the investigators looking for the killer.

"Everyone is extremely cautious and staying close to home," Gaffney City Administrator James Taylor said. "It certainly, certainly has put a damper on Fourth of July weekend celebrations."

Investigators asked anyone with tips to call the Cherokee County Sheriff’s Office at 864-489-4722 or Crimestoppers at 864-489-2746.

FOXNews.com's Catherine Donaldson-Evans and The Associated Press contributed to this report.