If I remember correctly, you, Heroes, and Loc urgently needed transportation. You found a house belonging to some ordinary family (yes, with children), and there was a bus in the yard. You got rid of the family and appropriated the bus.
(Seriously, I've never stolen buses from anyone; I don't know where that came from. I only subdued benefactors, followed by their deaths in a fire, to get some money, that's all.)