There are at least 40 Americans – far more than previously believed – actively serving in the Islamist terror group Al Shabaab, including dozens of radicalized killers from Minnesota’s prominent Somali-American community, experts told Fox News. "In Minnesota, you have a very large Somali-American community, so Al Shabaab is attracted to potential recruits there,” said David Ibsen, executive director of the U.S.-based Counter Extremism Project, a nonprofit co-founded by former Sen. Joe Lieberman, I-Conn.