A non injury unintentional roof fall occurred on the MMU No 1003 section.The roof fall occured during retreat mining. The roof fall was located in the #13 entry 2 crosscuts inby survey station # 8263. The roof fall entrapped the cont. miner and the shuttle car. The roof fall was approx. 4-8' thick X 18' wide X 18' long. MSHA was notified.