My sourdough bread left out on the counter to rise before baking attracted fruit flies. How do you rid of them?

I only left it out for over night covered with a towel. I don't have bugs, but on the rarity. I've only seen 2 fruit flies. I think that is what they are. But once you see a couple there ends up being a lot just like roaches. How do I get rid of them so they don't bring their entire plantation over night???????