You truly surprised? They've been here for years and I'm sure there are many more throughout the city of various backgrounds and ties to what most think only exist "over there." These guys are a prime example.
https://www.cnn.com/2015/05/04/us/garland-mohammed-drawing-contest-shooting/index.html
"A day after police killed two gunmen who tried to ambush a Garland, Texas, event featuring controversial cartoons of the Muslim Prophet Mohammed, details began to emerge about the shooters.
...
He also was no stranger to federal investigators. In 2011, he was convicted of making a false statement involving international and domestic terrorism. The other suspect, identified as Nadir Soofi by two federal law enforcement officials, was Simpson's roommate in a Phoenix apartment.
He wasn't well-known to federal law enforcement and was not on the FBI's radar, one of the officials said."