Sounding groggy but calm, the Marshall County deputy sheriff radioed in from his patrol car at 2:19 a.m. on a lonely country road in northwest Minnesota.

"Something just hit my car," said Val Johnson. "I don't know how to explain it. Strange. … Something attacked my car."

He'd seen a bright light in the sky, he said, visible for miles across the flat prairie, and drove toward it to investigate.

Fellow officers listening in quickly got on the radio and began speculating about what had happened. Perhaps he'd been hit by a small car, one suggested.

Johnson cut them short.

"It wasn't a vehicle," he snapped. "I don't know what the hell it was."

Four decades later, nobody else knows what the hell it was, either. But that won't keep Warren from celebrating the biggest mystery to hit this town as far back as anyone can remember.

Tuesday marks the 40th anniversary of Johnson's brush with a UFO, which drew national attention to this town of 1,500 residents near the North Dakota border, some 320 miles northwest of the Twin Cities. The incident has been called one of the Top 10 most significant UFO encounters ever recorded.

The county historical museum, where Johnson's rust-colored Ford LTD squad car is the star attraction, will host a presentation featuring a re-enactment of his radio call that night. Several ufologists will be on hand, as well as the dispatcher who spoke with Johnson that night.

There will be an alien costume contest for the kids, and the Jensen Sisters from Thief River Falls will perform their original song "The Marshall County Incident."

Sherlyn Meiers, the museum director, says interest in the event has been strong.

"I have been getting phone calls almost every day for the past month," she said. "Maybe we're gonna have a bigger crowd than we thought."

The light 'went at' him

Johnson, 35 at the time, had been with the Marshall County Sheriff's Department for almost three years. Quiet and well-respected, he'd been making a routine patrol on rural roads when he saw the light in the night sky, just across the Red River from Grafton, N.D. He wondered if it might be an aircraft from the nearby Air Force base in Grand Forks, N.D.

Johnson drove toward the light. The next thing he knew, some 40 minutes later, he woke up. His eyes and face were burned — doctors later described them as welder's burns — and he had a lump on his forehead.

The windshield on Johnson's squad car was cracked in a spiderweb pattern; there was a hole in one of his red flashers and a dime-sized dent in the hood. Two antennas were bent between 45 and 90 degrees.

Both the electric clock in his car and his windup Timex wristwatch had stopped for 14 minutes. He had synchronized them at the start of his shift, as he did every day.

Describing the incident later, Johnson said he saw a bright light about a foot across, hovering about 3 feet off the ground. Suddenly, he said, the light "went at" him and white light engulfed the vehicle.

Sheriff Dennis Brekke wasted no time calling in experts to investigate. Within days, Warren was visited by a metallurgical engineer from Honeywell, a glass expert from the Ford Motor Co., a consultant in hyperspectral imagery from a Brainerd laboratory — and Allen Hendry, a ufologist from the Center for UFO Studies in Chicago.

The experts could only speculate on the cause.

"It's hard to find one neat explanation," Hendry said at the time. The Ford glass expert called the pattern of windshield cracks "extremely unusual," adding that he'd never seen anything like it.

The engineer said the "best fit" for all the physical evidence pointed to "a highly charged electrical 'thing' with enough mass and momentum to create the effects."

Ultimately, Brekke closed the investigation without reaching any conclusions. Over the years, the original case file and the audio recording of Johnson's dispatch call have vanished from the sheriff's files, though the museum has copies of many of the documents and portions of the audio recording.

'This is what happened'

While Tuesday's celebration is expected to draw many people to Warren, Johnson, now 75 and living in Eau Claire, Wis., isn't expected to attend. In the months after the incident, he gave dozens of interviews. The National Enquirer offered him $1,000 to go under hypnosis. He declined.

He did appear on "That's Incredible," a popular TV show at the time, during which he re-enacted the event.

"Upon reflection, we've [his family] come to the conclusion that perhaps the creator has made other things that we can't see or readily identify," he said on the broadcast.

After that, he declined further interviews and rarely spoke publicly about the incident.

Johnson wasn't available for a recent interview, but he did sit down last year with a reporter for VolumeOne, an Eau Claire-based culture magazine.

"For the first three years, it was on my mind daily," he said. "After that I went on with my life. … It's not a defining incident in my life."

To those who suggested he made up the story to win publicity, he had a ready reply.

"I'm not running for public office; I don't have vitamins to sell you," he said. "This is what happened to me. If you choose to believe, great. If you choose not to believe, that's OK, too."

In Warren, these many years later, people still don't know quite what to think.

"I don't not believe it," said Lori Benitt, a staff member at the museum.

"Some people are like, 'It's a bunch of crap,' and other people are really into it," said Meiers, the museum director. "I think the universe is so huge, who knows what's out there? It's a possibility. There's lots of things that are pretty strange."