Schools in several Kentucky counties are closed as the search for a man suspected of shooting into vehicles along a major highway, injuring five people, continued into a third day.

The suspect, Joseph A Couch, 32, was charged Monday with multiple counts of attempted murder and assault.

After the incident on Saturday evening, police believe the attacker fled to a remote rugged area about 9 miles (14km) from the city of London in south-eastern Kentucky.

The Laurel County Sheriff’s Office said that they had recovered a silver Honda SUV and an AR rifle they believe was used in the attack, although the suspect may have other firearms.

Police also found a phone they believe belongs to Mr Couch, but the battery had been removed.

An arrest warrant was filed for Mr Couch, charging him with five counts of attempted murder and five counts of first-degree assault.

Hours before the shooting, Mr Couch legally bought the rifle and about 1,000 rounds of ammunition, police said.

The shootings began at about 17:30 local time (21:30 GMT) on Saturday. Police initially said nine vehicles were hit by gunfire along Interstate 75, a busy north-south route. They later increased that number to 12 cars.

The shots were fired from a ledge on a cliff overlooking the highway.

Five people were wounded and some had "very serious" injuries, officials said, including one person who was shot in the face.

All were stable as of Sunday and were expected to survive.

Randall Weddle, the mayor of London, Kentucky, said that some local businesses and churches remained closed Sunday while the manhunt continued.

Authorities warned local residents to be vigilant while the suspect is still at large.

“You need to lock your doors,” Kentucky State Police spokesperson Scottie Pennington said Sunday. “If you have security cameras, make sure you’re constantly watching them, maybe keep your porch lights on.”

As a precaution, schools in Laurel County, where London is located, and several neighbouring counties were closed Monday.

Officials said the woods in the area are very thick and the search is slow. The hunt was suspended after dark on Sunday night, but officers remained in a wooded area near exit 49 on I-75 in an attempt to contain the suspect.

"That's probably one of the most remote exits on I-75," Deputy Gilbert Acciardo of the Lauren County Sheriff’s Office told reporters during a news briefing. "It's a big task.”

Mr Acciardo described the scene as a "madhouse" when first responders arrived.

“People on the sides of the road, emergency flashers going, bullet holes, windows shot out,” he said. “Can you imagine that? Just chaotic.”

Police said they have not yet determined a motive for the shooting, but they have characterised it as a random attack rather than a targeted one. Mr Couch previously served in the National Guard, according to police.

An Army spokesperson said Mr Couch served in the Army Reserve for roughly six years, from March 2013 to January 2019, as a combat engineer, but was never deployed.

The city of London has about 8,000 residents and is near the Daniel Boone National Forest.

Speaking to CNN, Christina DiNoto, who was driving on I-75 with a friend at the time of the shooting, said "it was like a rock went through my back window", hurting her ear.

"We looked at each other and we were like, 'Was that a gunshot?' And then we’re like, 'No, that wasn’t a gunshot.'"

She said it was only an hour and a half later they learnt that there had been a shooting.

Kentucky's Governor Andy Beshear wrote on social media that the area should be avoided, and urged the public to "pray for everyone involved".