Officials say a boat carrying about 50 people has capsized while crossing a river in central Indonesia, leaving at least two people dead and dozens believed missing.

Rescue official Mujiono, who uses one name, says 11 people were rescued after the boat sank Wednesday in the Mahakam River in East Kalimantan. He says the bodies of two women were recovered.

The boat was believed to be carrying about 50 workers. National Disaster Mitigation Agency spokesman Sutopo Purwo Nugroho said the exact number of missing was unclear because no passenger manifest exists.

Rescue efforts were hampered by strong winds and currents.

Ships are a key mode of transportation in Indonesia, the world's largest archipelago. Boats are often overcrowded and in poor condition.