>>7>>6>>5 Like all of y'all said, it's very possible it was just a random act of violence.
But just consider this, what if terrorist (I am not using the term as a classification that discern a certain group of people sharing ideals, ethnicity, or political goals) try to attack in a different form. To still carry out an attack ,but allow Islam as a whole to come out of public opinion unscathed, they could use the fact that is was more sociopathic than an attack in the name of their goals. Similar to how some gangs and crime rings use mentally handicapped people to carry out assassinations and various other crimes to still complete a task but not link the entire group (Taliban, Mujaheddin, Bloods or who ever the head group is) to the crime committed.
But I usually hate to pin things like this on terrorism, just brought it up as an interesting theory.