The man suspected of opening fire on cars traveling along Interstate 75 in rural Kentucky was at large on Sunday night after a daylong manhunt by multiple law enforcement agencies through rugged, wooded terrain.

Kentucky State Police was leading the manhunt for suspect Joseph Couch, 32, whom police identified after finding a vehicle registered to him and an AR-style rifle near the shooting site, about eight miles (12.9 km) from the city of London in southeastern Kentucky.

Five people were injured in the shooting spree but are in a stable condition. One victim was shot in the face and another in the arm.

Couch is believed to have purchased his weapon and ammunition on Saturday morning, Laurel County Sheriff Captain Richard Dalrymple told reporters at a Sunday night press conference.

Couch is alleged to have started shooting from a cliff above a remote stretch of the interstate at around 5:30pm on Saturday, officials said. At least 12 vehicles were hit.

“We’re not going to stop on this case until we do find him and take him into custody,” said Michael Stansbury, Special Agent in Charge at the Federal Bureau of Investigation’s Louisville, Kentucky field office.

Police are still investigating the motive for the shootings.

Local residents were urged to lock their doors, stay vigilant and avoid the manhunt area, where police believe Couch is contained and armed. Couch, from southern Kentucky, served in the National Guard for four years and was a member of the engineer battalion, Dalrymple said. He had no serious criminal record.

Dalrymple said ground teams paused their search of thousands of wooded acres when darkness fell on Sunday because of the dangers presented by the rugged terrain, but patrols would be stationed around the area’s perimeter.

Search teams were using a helicopter and a drone with infrared technology, and federal, state and local agencies were on the case.

Laurel County public schools canceled Monday classes out of an abundance of caution.

The shooting took place three days after two students and two teachers were killed, and nine others wounded, at a high school in Winder, Georgia.