An unknown number of people were missing Sunday after a water bus carrying up to 40 passengers sank in a river in the Bangladeshi capital Dhaka, police said.
Police said the bus was ferrying people across the Buriganga at around 8pm (1400GMT) when it was hit by a cargo vessel carrying sand near Sadarghat, Bangladesh's largest river port.
Prothom Alo, the country's largest Bengali daily, said that between 25 and 30 people were missing.
One woman who swam ashore told AFP her daughter had yet to be found.
"She does not know how to swim," said Mokseda, who has only one name.
"Can you tell me what happened to her?" she asked from the marine police station at Sadarghat.
Police sub inspector Hasan Ali said that at least four bodies had been recovered and several survivors had been interviewed.
"They said up to 40 people were aboard the water bus when it was hit by a bulkhead sand-carrying boat," he said.
"We don't know how many people are still missing. The rescue operation is going on. Fire service divers are at the scene," he added.
Rescued passenger Imran Hossain told Prothom Alo he believed the water bus had been carrying more than 50 passengers.
"I sat on the roof as there was no vacant seat," he said.
Maritime accidents are common in Bangladesh, a delta nation crisscrossed by hundreds of rivers.
Experts blame poor maintenance, lax safety standards at shipyards and overcrowding for many of the accidents.
Vessels transporting sand sit low in the water and can be hard to see in choppy conditions, particularly when light is poor.