Any tips on housebreaking 2 puppies at once?

I have 2 16 week old pups and housebreaking is NOT going well. They are crate trained and clean in the crate. They will go outside and have even learned to come get a treat after. BUT they still go in the house. I take them out every hour or if they start snifiing. If I catch them I say No NO to startle and rush them out. But STILL given the chance they will dirty in the house. I am so frustrated!