brakes locking up

so i was driving today and i go to stop at a stop sign and the brakes lock up on me. I pressed the brake like normal but they locked up. Im thinking it might be from the other night cause i drove through some deep water, prob up to the bumper, but the brakes were fine until today. They locked up today twice, if yall could help me out with what this might be i would greatly appreciate it. Thanks
scott

My rears were locking up on me, on two different occasions. One was a broken retracting spring and the other was a leaking wheel cylinder. Shoes were fluid soaked and I´m quessing there was a little air in the cylinder, that was keeping the cylinder from returning to the rest position.
Anytime I get in the mud or water, I clean the sand out of the drums, saves a lot of money on shoes and wear and tear on the drums.