Big Brother US: What happens when it gets down to final four?

So this Thursday, it will be a double eviction and 2 housemates will go home. That will only leave 4 players. Do they still do HOH and Veto until it is down to 2? It just doesn't seem like it would make much sense, because with 4 people, 2 would be nominated and 1 HOH, so only the 1 person would be voting on the eviction. Then, when it is down to 3, would the HOH decide? I only watched a season a long time ago, so any insight would be great! Thanks!