The young men who attacked that shopping mall in Nairobi were members of a terrorist group called al Shabab - which means "The Youth." They are ultra-conservatives who ban music and videos. Men are forbidden to shave, women are forbidden to wear bras.
But what's really shocking is al Shabab has managed to attract Americans.
I found a video from an al Shabab called "The Path to Paradise." And if you wonder why an American would join, here's your answer.
"I can only tell you that you have the best of dreams, you eat the best of food, and you're with the best of the brothers and sisters. This is the real Disneyland," explains Troy Kastigar in the video. He's from Minnesota and he took the name Muhammad al-Amriki ("Mohammed the American.")
"We walk amongst the lions," he is heard saying in the video.
According to the video, he went to Somalia in 2008. "You need to come here, forsake your desires so you can die."
Sure enough, by the end of the video he'd been shot - and we see his friends praying over his body.
So that's a heck of a recruiting pitch: Come to Somalia, walk with the lions, and get shot. So why do they do it?
Here's what a leader of the Somali community in Minneapolis told CBS's Dean Reynolds. "It's about engaging a young man who is lost. They hold his hand. They take him to the mosque. They give him a target."
Alienated young men - the universal raw material for just about any kind of violence.