(CNN) -- One person died when a pipe bomb exploded outside a nightclub in West Virginia early Saturday morning, state police said.
The incident, which took place at Cactus Joe's in Barboursville in the southwestern part of the state, occurred around 2:30 a.m.
"We have an individual that brought explosive devices outside of the business. One of the devices detonated, proving fatal for the individual," Cabell County Sheriff Tom McComas said. "I don't know an exact age of the victim. We're still in the infancy of this investigation."
Police evacuated as many as 100 people from an apartment complex, mobile home and 20 to 25 houses while they searched for other bombs, police officers said.
Angie Ferguson, assistant supervisor of Cabell County 911, said authorities found another pipe bomb that had not been detonated. She said there were no other casualties from the incident.
Authorities said they have a theory about what happened, but were unwilling to elaborate on any details.
"It would be imprudent for me to speculate at this point if the bombing was an act of terror," McComas said, adding "it was strange activity" for the working-class town, which sits eight miles east of Huntington.
"We are still in the process of rendering the area safe. We anticipate that to take another hour to three hours," McComas said. "We have a major U.S. route that runs through here, Route 60...we have about a mile of it shut down until we can get the area safe," he said.
Police were examining a sport utility vehicle the victim was believed to have driven to the club, McComas said.
Ferguson called the blast an "isolated incident" and said it was unlikely that the explosion was related to terrorism. "We don't have much of that here."