Police say that the driver of an SUV that plowed through a Christmas parade in Waukesha, Wis. Sunday, killing five people and wounding 48, did not appear to know anybody in the parade.

At a news conference Monday afternoon, Waukesha Police Chief Dan Thompson said police are “confident” that the suspect, identified as Darrell E. Brooks Jr., 39, acted alone, and there is “no evidence this is a terrorist incident.”

Car-ramming incidents have become all too familiar in the United States and around the world.

They have an explicit endorsement from the Islamic State, for instance, as they are relatively simple and inexpensive to carry out — but can cause great harm if done in very crowded areas. They are also becoming a more prominent tool in attacks against protesters by far-right or far-left groups.

One of the most well-known such incidents occurred in 2017, when avowed neo-Nazi James A. Fields Jr. rammed his car into a crowd of counterprotesters at a white-supremacist rally in Charlottesville, killing one person and injuring 35 others.

In a June 2021 report, the Counter Extremism Project, a nonpartisan research and advocacy group based in New York, said attacks against protesters using cars are most often the domain of the far-right, although “some were also perpetrated by those on the left against right-wing protesters.”

“Authorities recorded at least 50 vehicular rammings against protesters between May and June 2020,” it said, including at least 18 “deliberate attacks.”

There are other reasons, too, that led to deadly crashes into packed areas — a man was convicted of capital murder in 2015 after he ran his car through crowds in Austin, killing four people while intoxicated and attempting to evade a police checkpoint the year before.

CEP tallied “at least 57 vehicular terrorist attacks since 2006, collectively resulting in the deaths of at least 207 people and the injury of at least 1,133 others.” It said these types of attacks are not new but have become more common “in large part” due to “ISIS’s explicit calls to employ cars as weapons.”

Some high-profile examples include a man who was alleged to have killed eight people and injured at least a dozen when he reportedly drove a truck into pedestrians and cyclists on a Lower Manhattan bike path in 2017. Federal officials charged him with providing support to a terrorist organization, alleging that he was inspired by the Islamic State.

In 2016, an Ohio State student drove a Honda sedan through a crowd on campus, injuring 13 people, before emerging from the vehicle and slashing at a police officer and others with a butcher knife. While his motives were not clear, his social media posts indicate he was frustrated with what he perceived as injustices committed against Muslims around the world.

There are international examples, too: In July 2016, a terrorist in Nice drove a truck into a crowd of people celebrating Bastille Day in the French Riviera, killing 86. In December of that year, a man rammed a vehicle into a Christmas market in Berlin, killing 12.

In March 2017, a man plowed a vehicle into pedestrians on Westminster Bridge in London, leaving four dead and 50 injured. And in 2018, a man used a rental van to run over pedestrians on a street in Toronto, killing 10 and severely injuring 16 people.

“Terrorists rely on a lot of people watching — it can be even better than having a lot of people dead,” Frank Foley, a scholar of terrorism at the Department of War Studies at King’s College London, told The Post in 2017 after the Westminster Bridge attack.

The challenges of mitigating such attacks — which are often enacted by lone-wolf attackers — using tools most people use in their everyday lives have preoccupied law enforcement for years.

“How do you stop someone driving down the street who just decides to drive their car into pedestrians?” Steve Hewitt, who studies surveillance and counterterrorism at the University of Birmingham, asked in 2017.

The answer to that question has become increasingly vital in the past few years, as terrorists have begun to shift tactics. In the past, the focus was on large-scale, spectacular attacks that involved scores of people and meticulous training.

More recently though, groups like the Islamic State and al-Qaeda have called for more spontaneous acts of terrorism by any means necessary. And these groups have highlighted the potential of automobiles not as car bombs, packed with detectable explosives, but as unpredictable ramming weapons.

The Department of Homeland Security has issued a guide for those seeking to mitigate the risks of vehicle attacks. The agency recommends making it clear where entry and exit points, first-aid stations and shelter locations are situated; assigning pedestrian-only zones and implementing strategies to slow the speed of traffic around them; using various kinds of vehicle barriers “to increase standoff distances between large crowds and vehicles”; and ensuring that staff working the area have been properly trained, while “recently terminated employees” have been vetted “to determine whether they pose a security risk.”

Those caught in such an attack should immediately “run to the nearest safe area while moving away from” the car, the agency says, or if that is not possible, “curl into a protected position and try to get up as soon as possible to avoid being trampled.”

“If no rapid escape is possible, seek cover behind any available natural or artificial objects that eliminate direct line of sight from the source of hazard,” Homeland Security recommends. Call 911 and “remain alert for potential secondary attacks,” while helping others and waiting for law enforcement to arrive.

Amanda Erickson and Isaac Stanley-Becker contributed to this report.