Attacks by violent members of the American far right were more likely to kill or injure when perpetrators used guns than when they used bombs or other weapons, a review of 25 years of extremist incidents shows.

A majority of attacks committed between 1993 and 2017 using solely firearms were successful, with 37 out of 55 total incidents resulting in deaths or injuries, according to data provided to The Trace by the Anti-Defamation League (ADL). The group, a nonprofit that combats anti-Semitism and other bigotry, examined the attacks in a May report titled “A Dark and Constant Rage: 25 Years of Right-Wing Terrorism in the United States.”

The 37 shooting incidents described by the ADL resulted in 68 deaths. The deadliest was in June 2015, when a 19-year-old white supremacist shot and killed nine black worshippers at a prayer group in a Charleston, South Carolina, church. President Barack Obama delivered a eulogy for the victims of that attack. In the aftermath, many Southern states began to remove iconography associated with white supremacy and the Confederacy from public facilities.

Most other attacks have gotten far less attention. In September 2011, two white supremacists went on a three-state killing spree from California to Washington that resulted in four deaths. The following year, seven members of the “sovereign citizen” movement, which denies the legitimacy of almost all government, ambushed and killed two sheriff’s deputies in LaPlace, Louisiana.

The ADL report was released amid newly heightened concerns about an emboldened right-wing extremist threat, and heated rhetoric from a handful of Republican lawmakers that groups like the ADL say could provoke violence. On June 4, Clay Higgins, a controversial former police officer and current U.S. representative from Louisiana, wrote on Facebook that “all of Christendom is…at war with Islamic horror,” and that America should “hunt” and “kill” Muslims.

The report builds on past research on extremism that has found that 95 percent of lives lost to terrorism on American soil since 9/11 were claimed by firearms.

The Anti-Defamation League considers an attack “successful” if it resulted in deaths or injuries, in the case of a gun or knife attack; a detonation, in the case of a bomb attack; or a fire, in the case of incendiaries. In compiling incidents from the report, the group tallied 150 right-wing terrorist acts, attempted acts, and plots and conspiracies carried out by white supremacists, anti-government extremists, anti-abortion extremists, and other types of far-right extremists.

Most acts were committed by a small number of extremists acting on their own rather than at the behest of organized groups. About half of the 150 incidents were committed by lone-wolf offenders, the ADL said. Right-wing extremists killed 255 people and injured more than 600 more in the incidents counted by the group.

Explosives were far less likely to have the intended result than attacks carried out with other weapons. The study’s authors found that only nine of 55 attempts by the far right to blow up people or property actually resulted in a detonation, nevermind actual death, injury, or destruction of property.

Explosives have killed more people than any other method due almost entirely to a single incident, the 1995 Oklahoma City bombing. That attack killed 168 people in what was the worst act of terror on American soil before September 11, 2001. The next-deadliest bombing examined in the report killed one person.

The ADL also found that attacks using only guns were more successful than those using “other weapons,” which includes those committed with knives or a combination of both explosives and guns. Only 10 of 27 incidents involving other weapons succeeded.

The only method of meting out destruction that succeeded more often than guns were incendiary devices, like molotov cocktails, which are designed to ignite fires. Incidents by far-right extremists using incendiary devices were successful 10 out of 13 times. However, such attacks were also the least common, and never resulted in deaths.

Guns are easier to access and they are more reliable than explosives, which take some amount of technical sophistication to assemble and successfully detonate, and which can be unstable, detonating at the wrong time, or not at all. Explosive materials like ammonium nitrate, a key ingredient in both fertiliser and the truck bomb used in the Oklahoma City attack, are also heavily regulated.

The report’s authors said that attacks using explosives — with the exception of Oklahoma City — may claim fewer lives because they are often used to target property, not human beings.

“Right-wing terrorism is a subject under-covered by the media, in part perhaps because so many right-wing terror incidents take place far from major media centers and urban areas,” the ADL report concludes. “One consequence of this relative lack of coverage has been an inadequate awareness among policy-makers and the public alike of the threat that violent right-wing extremists pose.”

The Trace is one of several dozen news organizations that has partnered with ProPublica to track hate crimes and other bias attacks. The project is called Documenting Hate.