At least 32 people have died and scores are missing after a ferry with some 200 people on board sank in a southern Bangladeshi river, police say.
About 50 people swam to safety after the accident in the Meghna River, south-west of the capital Dhaka. Divers have recovered many of the bodies.
The Shariatpur-1 capsized after colliding with a small oil tanker.
Ferry accidents are common on Bangladesh's vast river network and scores are killed every year.
Hundreds of people, including some desperate relatives, gathered on the river banks during the rescue operation as bodies were extracted from the water.
Police fear more bodies could be trapped inside the vessel, which passengers said sank rapidly after the collision early on Tuesday morning.
The BBC's Ethirajan Anbarasan - who is on a boat at the scene of the disaster - says that the river is about 64km (40 miles) wide with a strong current. The ferry is believed to be in water about 70ft (21m) deep.
Our correspondent says it is not possible to say exactly how many people were on board, because passenger lists are rarely compiled on Bangladeshi ferries and many buy their tickets when on board.
The ferry was reportedly travelling to Dhaka from the Shariatpur district.
Some of the rescued passengers said that it was overcrowded and was also carrying dozens of sacks of chillies.
One survivor, Mohammed Belal, told the BBC the ferry turned almost upside down because of the collision.
"Some of us managed to jump out through the windows," he said, "and some of us were hanging by the rails".
"We yelled 'save us, save us' and that's when another ferry threw some ropes into the water.
"Everybody was frantically running around. Some of us were able to jump out but many didn't."
Most ferry accidents in the country are blamed on poor safety standards and overcrowding.
Shahabuddin Milon, deputy head of the Bangladesh Inland Water Transport Association, told the BBC's Bengali Service that many cargo boats flout the law banning them from night-time travel, endangering passengers.
Officials say the rescue operation is continuing overnight on Tuesday under floodlights.
Last April, at least 23 people died after a ferry carrying more than 100 passengers capsized in the east of the country.
In June 2010, about a dozen people were killed after a packed ferry capsized in storms in north-east Bangladesh and in November 2009, 118 people died in two ferry accidents within a week.
Boats are the main form of travel in parts of rural Bangladesh - a country that is crisscrossed by rivers and waterways.
The authorities are repeatedly criticised for failing to honour their pledges to tackle lax safety standards.
Local government spokesman Azizul Alam said that an investigation has been ordered into the cause of the latest sinking.