More than 200 people have been rescued from the sea after a heavily-loaded ferry sank off the coast of Indonesia.
But at least 23 people died and an unknown number of others are missing after the accident, which officials blamed on bad weather and high waves.
Some reports suggested the ferry, which had a capacity of 273 people, may have been overloaded.
Search efforts have now stopped for the night but officials say they will resume in the morning.
'Traumatised'
Indonesia's sea transport director-general, Sunaryo, said rescue efforts had been hampered by bad weather.
"The waves are as high as six metres, it's difficult for small ships to reach the location," he told a news conference in Jakarta.
The Dumai Express 10 was travelling from Batam island to Dumai in Riau, Sumatra, when it sank.
Officials said it rolled over before capsizing about 90 minutes into its voyage.
According to its manifest, about 240 people were on board the Dumai Express 10 ferry when it sailed, but it is not clear if this was accurate.
Rescue efforts were aided by the fact that the ferry went down in the busy Malacca Straits between Indonesia and Malaysia.
It is not clear exactly how many people have been picked up.
The chief of police in Riau told the BBC that 218 had been rescued; earlier other officials gave totals of 292 and 232.
The total number of people on board the vessel remains unknown.
A navy spokesman said it was not clear whether anyone was still inside the ferry, which was now completely submerged.
"We're not sure if anyone is trapped in the ferry. Those who have been rescued are traumatised," Iskandar Sitompul said.
Another ferry, the Dumai Express 15, was reported to have run aground in bad weather as it travelled between Batam and Moro islands.
All 278 passengers and crew on board were said to be safe.
Ferry accidents linked to over-crowding and poor vessel maintenance kill hundreds of passengers in Indonesia each year.
The country's large population is spread out over 17,000 islands and relies on ships and ferries to travel around.
In the last three years, at least 800 people have been killed in ferry accidents in Indonesia.


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