LONDON, Ky. (AP) — As a grueling manhunt stretched into a third day Monday for a suspect in an interstate shooting that struck 12 vehicles and wounded five people, authorities vowed to keep up a relentless search as the stress level remained high for a rural area where some schools canceled classes.

Authorities have been searching a rugged, hilly area of southeastern Kentucky since Saturday evening, when a gunman began shooting at drivers on Interstate 75 near London, a small city of about 8,000 people located about 75 miles (120 kilometers) south of Lexington.

The search was temporarily suspended once darkness fell Sunday night, but was set to resume Monday morning.

“We’re not going to quit until we do lay hands on him,” Laurel County Sheriff John Root said Sunday night.

Joseph A. Couch, 32, was named first as a person of interest and later as a suspect in the shooting after authorities said they recovered his SUV on a service road near the crime scene. They later found a semi-automatic weapon nearby that they believe was used in the shooting, said Deputy Gilbert Acciardo, a spokesperson for the local sheriff’s office.

On Sunday, as another day of searching was ending without any sign of the suspect, Acciardo acknowledged the frustration that law enforcement officers and people who live near the search area are feeling.

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“As this continues, it becomes more stressful for the community, it becomes more stressful for the officers that are there because we’re looking ... and we’re trying to find him, and we haven’t found him,” he said.

State police Master Trooper Scottie Pennington, a spokesman for the London state police post, said troopers are being brought in from around the state to aid the manhunt. He described the extensive search area as “walking in a jungle” with machetes needed to cut through thickets of woods.

Acciardo said it appears that the attacker planned the shooting for that location because it is very remote and the terrain is hilly, rocky and hard to navigate.

With the gunman still at large, numerous area school districts canceled classes for Monday. Pennington urged area residents to lock doors, keep porch lights on and monitor security cameras. The search was focused on a remote area about eight miles north of London.

Authorities sought to reassure residents that they believe the suspect will be found.

“We’re doing everything that we can do,” Root said, adding, ”Just be confident.”

Authorities said Couch purchased the weapon and about 1,000 rounds of ammunition Saturday morning in London. Couch has a military background, having served in the National Guard for at least four years, said Capt. Richard Dalrymple of the Laurel County Sheriff’s Office.

Authorities initially said nine vehicles were struck by gunfire, but later increased that number to 12, saying some people did not realize their cars had been hit by bullets until they arrived home. They said the gunman fired a total of 20 to 30 rounds.

Couch most recently lived in Woodbine, a small community about 20 miles (32 kilometers) south of the shooting scene. Acciardo said authorities found his abandoned vehicle Saturday and then an AR-15 rifle on Sunday in a wooded area near a highway where “he could have shot down upon the interstate.” A phone believed to be Couch’s was also found by law enforcement, but the battery had been taken out.

Some residents of Laurel County were on edge as authorities searched with a drone, helicopter and on foot in a remote and sparsely populated wooded area near the busy interstate.

Cody Shepherd, sipping a bloody mary outdoors while waiting to watch a football game at the Pour Boyz Sports Lounge in London on Sunday, said locals were abuzz with speculation. A resident of London, he was at a party Saturday at a friend’s house about 10 miles (16 kilometers) south of where the shooting occurred.

“We were listening to the police scanners all night,” he said, adding they heard sirens and saw a helicopter overhead.

On Sunday, several local churches canceled services. But Rodney Goodlett, pastor of Faith Assembly of God in London, was helping direct traffic as parishioners gathered for a morning service. He expected the search would hold down attendance.

“This is tragic, obviously, that somebody would randomly do violent acts,” he said. “You hear media things taking place all around our country, but then when it hits home, it’s a little bit of a wake-up call.”

Acciardo said authorities are being inundated with tips from the public and are following up on each one in case it could help them find the shooter. When the search has been suspended at night, specially trained officers have been deployed in strategic locations in the woods to prevent the gunman from slipping out of the area.

“We’ve got to get him,” Acciardo said.