1. Killing on'e father, pha gsod pa, pitrighata
2. Killing one's mother, ma gsod pa, matrighata
3. Killing an arhat, dgra bcom pa gsod pa, arhadghata
4. Intentionally drawing blood from a buddha, de bzhin gshegs pa'i sku las ngan sems kyis khrag 'byin pa, tathagatasyantike dushtacitta rudhirotpadanam.
5. Creating a schism in the sangha, dge 'dun gyi dbyed 'byed pa, sanghabheda

As a result of one of these actions, one will immediately fall into the hell realms at the time of death. And prevents one from attaining enlightenment during that lifetime.