Editor's note: A previous version of this story included a photo of a protester being struck by a car in Louisville, Kentucky. The photo, chosen by editors, does not appear to be an example of the assaults described in the story, and has been replaced. Police have not charged the driver, but have charged two of the protesters involved in that incident. Authorities continue to investigate.

Right-wing extremists are turning cars into weapons, with reports of at least 50 vehicle-ramming incidents since protests against police violence erupted nationwide in late May.

At least 18 are categorized as deliberate attacks; another two dozen are unclear as to motivation or are still under investigation, according to a count released Friday by Ari Weil, a terrorism researcher at the University of Chicago's Chicago Project on Security and Threats. Weil has tracked vehicle-ramming attacks, or VRAs, since protests began.

The 20 people facing prosecution in the rammings include a state leader of the Virginia Ku Klux Klan, as well as a California man who was charged with attempted murder after antagonizing protesters and then driving into them, striking a teenage girl. Video footage of some attacks shows drivers yelling at or threatening Black Lives Matter protesters before hitting the gas.

"The message they're trying to send is, 'You need to get out of the street and stop these protests,' " Weil said. "They're trying to intimidate the most recent wave of BLM protesters, to stop their movement."

The last rash of vehicle rammings occurred in 2015 and 2016, Weil said, when the "Run Them Over" meme was popularized in far-right circles in response to Black Lives Matter protests and demonstrations against the controversial Dakota Access Pipeline.

The most high-profile attack occurred a year later, during the 2017 Unite the Right rally in Charlottesville, Virginia. A white supremacist plowed his car into a crowd, killing 32-year-old Heather Heyer and wounding dozens of others in a bloody weekend that jolted the country into recognizing the resurgent threat of far-right violence.

"The use of car attacks against peaceful protesters is increasingly a deliberate terror tactic for white supremacists," said Amy Spitalnick, executive director of Integrity First for America, a civil rights nonprofit that's leading a civil suit on behalf of Charlottesville ramming victims. The goal of the suit is to bankrupt and dismantle several hate groups that helped organize the rally.

"As detailed in our lawsuit, the Charlottesville violence was planned months in advance online — including discussions of hitting protesters with cars," Spitalnick said.

Weil said support for the attacks is not just seen in extremist channels but is also spreading in more mainstream Republican and conservative spaces.

After the Charlottesville attack, Fox News deleted and apologized for running a syndicated piece that encouraged car-ramming attacks. Originally published by the right-wing Daily Caller, the online article included a video montage of car attacks under the headline "Here's A Reel Of Cars Plowing Through Protesters Trying To Block The Road."

After public backlash, Fox News deleted the version that had run on Fox Nation. A Fox News executive told CNN Money that "the item was inappropriate and we've taken it down." The Daily Caller also deleted its original post.

"I want to caution that this isn't just a far-right, neo-Nazi thing, but it's becoming something that's encouraged broadly, and I think that should worry everyone," Weil said.

From May 27 to June 17, Weil recorded at least 50 vehicle-ramming incidents nationwide. Of those, five were by law enforcement and 45 by civilians. At least 18 of the civilian incidents involved malice, and another 23 remain unclear as to motive, according to Weil's analysis of police and court records, as well as news reports. The bulk of the attacks occurred in the first 14 days of protests.

"To see dozens of these incidents occur over two weekends was surprisingly high," Weil said.

Four were ruled accidental, including the viral incident when a tanker barreled down a highway in Minneapolis, sending terrified protesters running for their lives. Authorities later released the driver without charges, saying he had acted foolishly but did not deliberately target protesters.

Most of the recent rammings have been captured on video. The footage follows a grim pattern: Protesters are shown walking peacefully when, suddenly, a car or truck appears in the frame and hurtles toward the crowd. People run, crouch and scream, "Oh my God!" Then the driver either manages to speed off or is surrounded and set upon by the outraged protesters.

One ramming in Boston unfolded live on the local TV news, with the reporter at the scene saying, "Several people just got hit! Several people just got run over!"

Weil said he suspects his tally is an undercount because incidents go unrecorded.

Minnesota protester Nuny Nichols, for example, never reported what happened to her and a couple of friends on the night of May 30. They had just returned to St. Paul, Minn., after spending the day passing out food to protesters across the river in Minneapolis. The three of them — all black women — were walking to Nichols' place when they came to an intersection where a white man in an SUV was waiting at the light.

"He kind of like motioned for us to come, you know, like, come on," Nichols said. "So we started walking out. And as soon as we got right in front of his car, he just sped up."

Nichols and her friends screamed and ran. They escaped without being hit, but Nichols said she'll never forget what it felt like to have a car aiming for her body. She's convinced the driver knew exactly what he was doing.

"He deliberately did it," Nichols said. "It wasn't like, oh, he ran the light, or we walked, no. He literally waited until we got almost right in front of his car — then he put his foot on the gas and sped up."

Nichols said it was jarring to go from standing shoulder to shoulder with white protesters during the day to the evening's reminder of the hate that's out there. But because of the tensions between cops and protesters right now, Nichols said, she didn't report the incident.

Instead, she stayed in her bedroom for a day, too rattled to go right back to the protests. Nichols' sister died in 2014 after being accidentally struck by a car; Nichols said she couldn't shake the thought that her mother almost lost another daughter the same way.

"I've never been in a predicament like that before, where somebody just wanted to kill me," Nichols said. "He didn't know anything about me — he just tried to run me over."

Nichols searched online for information about rammings and discovered the disturbing forums that celebrate and encourage car attacks. She saw the recent news reports about a fire chief in West Virginia who was dismissed from his post for wearing a T-shirt showing a car hitting protesters and the words "All Lives Splatter." Nichols saved the chief's photo to her phone as a reminder that her experience wasn't isolated.

"I was, like, 'Wow,' " Nichols said. "It made me think about, maybe this is more of an actual thought-out process, a deliberate plan for them to run people over."

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