Updated

A manhunt for a gunman in Kentucky stretched into a third day on Monday as officers hacked through "jungle"-like terrain with machetes in search of a suspect who opened fire near Interstate 75 over the weekend, wounding five people, authorities said.

Officers have relentlessly scoured a rugged, hilly area of southeastern Kentucky since the shooting unfolded Saturday around 6 p.m. near exit 49. Officers have so far recovered an AR-15 rifle and a small silver-colored SUV registered to the suspect – 32-year-old Joseph A. Couch. Couch, however, remains on the run.

The extensive search area along the highway was like "walking in a jungle," with machetes needed to cut through thickets of woods, said State police Master Trooper Scottie Pennington, a spokesman for the London state police post.

As darkness fell Sunday night, the search once again ended without any sign of the suspect. The search resumed Monday morning with a focus on a remote area about eight miles north of London.

KENTUCKY POLICE RECOVER SUV, AR-15 IN MANHUNT FOR I-75 SHOOTER

Joseph A. Couch

Joseph A. Couch was named a suspect in the I-75 shooting after authorities found a vehicle registered to him near the crime scene. He was initially named a person of interest. (London Police Department)

"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," said Deputy Gilbert Acciardo, a spokesperson for the Laurel County Sheriff’s Office.

wooded search area

The terrain in the search area is hilly, rocky and hard to navigate, according to officials. (AP Photo/Timothy D. Easley)

Several school districts in the rural area canceled classes Monday out of an abundance of caution. Officials warned the public to lock doors, keep porch lights on and monitor security cameras.

law enforcement officer

Law enforcement agencies have relentlessly searched for Couch since Saturday evening. (Laurel County Sheriff's Office)

Couch was initially named as a person of interest before authorities found the vehicle near the crime scene.

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 sheriff's office.

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Investigators believe Couch fired a total of 20 to 30 rounds from a wooded area near the highway where Acciardo said "he could have shot down upon the interstate." Acciardo said Couch likely picked this location because it is remote with terrain that is hilly, rocky and hard to navigate.

wooded search area

Officials said the search area is a remote area about eight miles north of London, Kentucky. (AP Photo/Timothy D. Easley)

Bullets struck 12 vehicles and wounded five people, who were all in stable condition early Sunday, according to officials. Some of the victims had "very serious" injuries, including one person who was shot in the face. Two other people were hurt in a vehicle accident caused by the gunfire.

Officials said troopers are being brought in from around the state to aid the manhunt, and investigators have been inundated with tips from the public. 

traffic stopped on I-75

Traffic was stopped during an active shooting on Interstate 75 north of London, Kentucky, on Saturday. (Camden Mink/Mount Vernon Fire Department via AP)

Meanwhile, specially trained officers have been placed at strategic locations around the wooded area to prevent the suspect from slipping through their perimeter.

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

The Associated Press contributed to this report.