Police in Idaho were searching Thursday near a small town for a man suspected of shooting and killing a motorist along a desolate stretch of interstate highway in Utah.

Jonathan Llana, 45, of Los Angeles was being sought near Burley after crashing his car during a chase by authorities, Idaho State Police said, describing him as armed and dangerous.

Officials said they didn't know a motive for the shooting Wednesday night on a stretch of Interstate 84 called Rattlesnake Pass in northern Utah.

Llana was charged Thursday afternoon with one count of aggravated murder and one count of attempted aggravated murder, according to online Utah court records. The charging documents don't reveal much about the incident other than that Llana is accused at firing multiple rounds at the vehicle driven by the victim, Dennis Gwyther of Salt Lake City.

Gwyther and a passenger were traveling in a Range Rover from Salt Lake City to Boise, Idaho, for work, Utah State Bureau of Investigation Lt. Ryan Van Fleet said,

Llana owns a silver Volkswagen Jetta that Idaho troopers pursued until it crashed into a canal along Interstate 86, Van Fleet said.

The driver ran, and authorities were searching for him Thursday, with the assistance of a helicopter, officials said.

"We think he's still out there ... running through the fields," Van Fleet said during a news conference in Salt Lake City. "We really think we're getting close on this."

In Idaho, Cassia County Sheriff Jay Heward warned residents near the search area to be wary of strangers and asked them to report any missing vehicles.

"People should keep their doors locked and not let strangers inside their homes," Heward told The Times-News newspaper in Twin Falls, Idaho. "Don't pick up anyone when you are driving or befriend anyone."

Llana was described as 5 feet 10 inches (1.8 meters) tall, weighing about 150 pounds (68 kilograms), with black hair and brown eyes. He is described as armed and dangerous, but Heward said it's unknown whether he has a weapon in his possession. Utah law enforcement officials said a weapon was found inside the wrecked Jetta.

Van Fleet said there was no indication the two drivers had interacted before the Wednesday shooting.

The attack occurred after the Jetta and Range Rover cleared a traffic slowdown that resulted when two big rigs were side by side as one passed the other, Van Fleet said.

The passenger in the Range Rover called 911 to report the shooting and provided a description of the Jetta, which had a unique antennae, according to the Utah Department of Public Safety.

Another motorist — an emergency medical technician — stopped to help and confirmed the driver had died. The injured passenger was taken to a hospital.