Three children were among at least seven day-trippers killed when their bus plunged down a 160-meter ravine after colliding with a car in the north eastern Mexican state of Nayarit.
A further 21 people were injured in the crash which happened when the group was returning from a day at the beach.
The state's fire chief, Jose Alfredo Lopez Saucedo, told local media Tuesday that the crash happened Monday night after the car invaded the bus's lane on the Tepic-Puerto Vallarta Highway, close to the village of Las Guasimas.
The passengers were returning from Nayarit's Los Ayala beach to Guadalajara, the state capital of western Mexican state Jalisco.
The steep cliff made rescue work difficult, with several bodies scattered around the wreckage. The injured, eight of whom are very serious, were taken to hospitals in Nayarit state capital, Tepic.