White extremist ideology has been linked to some of the deadliest active-shooter episodes in the United States in recent years, showing the potential for intense violence among adherents who congregate online to cheer on racist attacks.

The suspect in the shooting rampage on Saturday at a Walmart store in El Paso was the latest to promote his ideology with an anti-immigrant manifesto posted minutes before he opened fire, killing 22 and injuring dozens more.

Active-shooter episodes with ties to white extremism

In the document, the suspect said he supported the actions of another gunman who killed 51 people at two mosques in Christchurch, New Zealand, this year. A man who opened fire at a California synagogue in April expressed similar sentiments, also in an online manifesto.

Both episodes highlight the growing international connections among white extremists, as well as a shift in what drives American mass shootings.

Global connections

A number of deadly white extremist shootings in the United States have been linked to similar white extremist attacks overseas. Circles show the number of people killed in all those shootings, and red circles and lines show connections from later attackers to the earlier attackers who influenced them.

El Paso Killed 22 Both the El Paso and Poway gunmen praised the Christchurch shooter in manifestos posted online. Poway, Calif., synagogue Killed 1 2019 Christchurch, New Zealand mosque Killed 51 Tallahassee, Fla. Killed 2 Pittsburgh synagogue Killed 11 2018 Aztec, N.M., high school Killed 2 2017 The shooter named previous attackers as influences. Quebec City mosque Killed 6 Munich mall Killed 9 2016 Roseburg, Ore., community college Killed 9 2015 Charleston, S.C., church Killed 9 Three killers made statements online supporting the Isla Vista attacker. 2014 Isla Vista, Calif., Killed 6 Overland Park, Kan., Jewish community center Killed 3 2013 Oak Creek, Wis., Sikh temple Killed 6 2012 Norway attacks Killed 77 2011 El Paso Killed 22 Both the El Paso and Poway gunmen praised the Christchurch shooter in manifestos posted online. Poway, Calif., synagogue Killed 1 2019 Christchurch, New Zealand, mosque Killed 51 Tallahassee, Fla. Killed 2 Pittsburgh synagogue Killed 11 2018 The Christchurch shooter said he was inspired by the Norway attacker. Aztec, N.M., high school Killed 2 2017 These two shooters corresponded directly. Quebec City mosque Killed 6 Munich mall Killed 9 2016 Roseburg, Ore., community college Killed 9 2015 Charleston, S.C., church Killed 9 Three killers made statements online supporting the Isla Vista attacker. 2014 Isla Vista, Calif. Killed 6 Overland Park, Kan., Jewish community center Killed 3 2013 Oak Creek, Wis., Sikh temple Killed 6 2012 Norway attacks Killed 77 2011 Both the El Paso and Poway gunmen praised the Christchurch shooter in manifestos posted online. El Paso Killed 22 Poway, Calif. Killed 1 2019 Christchurch Killed 51 Tallahassee, Fla. Killed 2 Pittsburgh Killed 11 2018 Aztec, N.M. Killed 2 2017 These two shooters corresponded directly. Quebec City Killed 6 Munich Killed 9 2016 Roseburg, Ore. Killed 9 2015 Charleston, S.C. Killed 9 2014 Isla Vista, Calif. Killed 6 Overland Park, Kan. Killed 3 2013 Oak Creek, Wis. Killed 6 2012 Norway attacks Killed 77 2011

Since 2011, suspects with ties to white extremism have carried out at least 17 active-shooter attacks, according to an analysis of F.B.I. and other data. The agency describes an active shooter as “an individual actively engaged in killing or attempting to kill people in a populated area.”

A growing list of attacks

White extremist assailants have opened fire at schools, at synagogues and at places of business. All but two of these attacks since 2011 proved fatal, but the El Paso shooting has been the deadliest so far.