Since Michael is an unstoppable force of evil, he survived the explosion at the end of Halloween II and has been in a coma ever since. Michael is in the process of being transferred between between hospitals when the inevitable happens- he decides to wake up. Naturally, everyone in the ambulance feels his wrath but the stand out moment for this kills goes to the poor attendant. He is literally under Michael's thumb. That's right, Michael is THAT strong he kills this poor fellow- who is only doing his job- by ramming his thumb into is skull.