Many of the dead were trapped on the lower deck of the pilgrim boat

Divers pulled at least two bodies from the bowels of a submerged river boat Monday after the overcrowded vessel carrying Muslim pilgrims sank on Thailand's Chao Phraya river, leaving 18 people dead.

The accident happened on Sunday afternoon near the ancient city of Ayutthaya, when a boat packed with pilgrims returning from a mosque hit a concrete bank in strong currents.