On Saturday, a firearm-wielding man massacred at least 11 people attending Shabbat services at the Tree of Life synagogue in Pittsburgh’s Squirrel Hill neighborhood and injured a number of others. The Anti-Defamation League described it as likely the deadliest single attack on the Jewish community in U.S. history. Authorities identified the suspect, who was captured after a gun battle with responding police, as 46-year-old Robert Bowers—a vitriolic anti-Semite who allegedly announced the attack on the social network Gab.