premise: A suicide attack is an attack in which the attacker or attackers intend to kill others and intend to die in the process (see suicide). In a suicide attack in the strict sense the attacker dies by the attack itself, for example in an explosion or crash caused by the attacker.
hypothesis: The attacker in a suicide attack wants to kill as many people as possible. 
reason: The passage didn't talk about them wanting to kill a lot of people... they may want to kill lots or some may just have a few people they want to kill. There is no way to know. 