the bombing the U.S. Marines barracks in Beirut, and I believe more than 200 Marines died in that attack.
And I believe there were several Americans killed in the bombing of the Pan Am 747 over Lockerby, Scotland.
And while he didn't kill anyone (not that he didn't try), the guy that stabbed 11 people at Ohio State was a Somali immigrant.
http://www.usatoday.com/story/news/2016/11/28/somali-immigrant-identified-attacker-ohio-state/94563226/