Either hang the food from a tree or raccoon hook, or lock it in your car. The car is better. Squirrels can and will chew through bags to get at your food.

You should also lock/hang anything with a food smell or fragrance. I've had raccoons make off with soap. It's best to keep your site completely clean and picked up; when you turn in for the night, you want EVERYTHING either in your tent or in the car.