There are two possible perpetrators of this act. One of them would be Islamic fanatics. The other, and this quite possible taking into account his past record, would be our ally, Pakistani President Pervez Musharraf. There are parliamentary elections coming on January 8th in Pakistan, and don't think for a minute that he won't take whatever steps deemed necessary to hold on to power.
The fact that you attribute all terrorism to Muslims shows a very narrow viewpoint of the world. While there are certainly many fanatical Muslims who are indeed perpetrating acts of terrorism, they had very good teachers. Ever heard of the Irish Republican Army? The Ku Klux Klan? The Army of God? The Kurdistan Workers Party (PKK)?