There was a dramatic surge in white supremacist violence in 2017.

White supremacists and other far-right extremists were responsible for 59% of all extremist-related fatalities in the US in 2017, according to the Anti-Defamation League’s (ADL) Center on Extremism. The ADL’s annual report—“Murder and Extremism in the United States in 2017”— found that the number of murders conducted by white supremacists US more than doubled last year, compared to 2016.

A spokesperson for the ADL explains that the report “looks at known murders or killings by perpetrators associated with domestic extremist movements. We are not accounting for all acts of violence, such as mass shootings.” However, if a mass shooting, such Charleston or San Bernardino, was found to be linked to an extremist movement and resulted in death, then the ADL would include it.

In total, extremists killed at least 34 people in 2017. The far-right accounted for 59% of these deaths, or 20 deaths. The report linked several killings to the alt-right movement, which expanded and moved its operations from the internet into the physical world last year. The chaos in Charlottesville, where a counter-protester, Heather Heyer, was killed and dozens were injured after a car driven by a white supremacist plowed into a group of pedestrians, marked the return of neo-Nazi street confrontations. The shift in tactic raises “the likely possibility of more such violent acts in the future,” the report notes.

Over the last decade, 71% of domestic extremist related killings in the US were linked to right-wing extremists, while Islamic extremists committed 26% of the killings, the report notes. An Islamic extremist committed the single deadliest incident in 2017: the New York City vehicle ramming attack killed eight people. Left-wing extremists and those who didn’t fall in the previous two categories carried out the other 3% of deaths. 2017 was the second year in a row in which black nationalists committed murders in the US.

Overall, there was a marked decline in the number of extremist killings last year from the much higher total fatalities recorded in 2016 and 2015. That said, the report describes 2017 as fifth deadliest year for extremist violence since 1970.