Female suicide bomber blows self up in middle of Shiite religious procession

This act is pure madness, madness and madness.
The most important thing is to figure how these suicide bombers reach the decision to blow themselves and kill other innocents.
What Shiite an Sunni religious division.

Female suicide bomber blows self up in middle of Shiite religious procession
A Shiite pilgrim inspects the scene of Friday's suicide bomb attack in Mussayab, south of Baghdad, Iraq. Dozens of people, mostly women and children, were killed in the explosion.
http://news.yahoo.com/s/ap/20090213/ap_on_re_mi_ea/ml_iraq