Renault Megane engine failure

When I was driving home yesterday, engine had a complete loss of power and would not restart. I was told my timing belt had gone and was towed home by breakdown service. When I looked at the engine this morning, the timing belt was still intact and tensioned. Is this normal as my understanding of a timing belt failure is either the belt snapping or becoming loose. Could there be anything else that could have caused this? The battery is fine as I checked this also. Thanks.