Mass killings in the U.S. by people with ties to extreme causes or movements have spiked significantly in the past decade, according to new research from the Anti-Defamation League (ADL).

Of 46 total extremist-related, ideologically-motivated mass killings identified by the ADL’s Center on Extremism in the more than five decades since 1970, 26 have occurred in the last 12 years alone.

The past decade saw at least three times more extremist-linked mass killings in the U.S. than any other 10-year period since 1970. While five were recorded in the first 10 years of the new millennium, 21 were recorded between 2011 and 2020.

Just two years into the tally for the next decade, 2021 and 2022 have already seen five extremist-related mass killings — as many as were seen in total between 2001 and 2010.

The ADL report says mass killings are “one of the largest threats that extremists pose to public safety today” following shootings last year in Buffalo, N.Y., where 10 Black people were killed in a grocery store, and in Colorado Springs, Colo., where five people were killed at an LGBT nightclub.

“Most of these mass killings were committed by right-wing extremists, but left-wing and domestic Islamist extremists were also responsible for incidents … Of particular concern in recent years are shootings inspired by white supremacist ‘accelerationist’ propaganda urging such attacks,” the report reads.

Domestic extremists killed at least 25 people in 12 separate incidents in the U.S. last year — 21 of those 25 murders were linked to white supremacists, which ADL notes as an “unusually high” figure.