As many as 192 passengers could be missing after a ferry sank into the depths of a volcanic lake in Indonesia, the search-and-rescue agency said Wednesday, tripling initial government estimates.
But the agency's head cautioned that it was still unclear how many people were aboard the vessel when it capsized Monday in Lake Toba, a popular tourist destination on Sumatra island.
The traditional wooden boat may have been operating illegally with no manifest or passenger tickets, sparking confusion and a string of changing official passenger estimates.
Indonesia's disaster agency originally said some 80 people along with dozens of motorcycles were on the overloaded, 43-passenger capacity vessel when it overturned and sank.
So far, four bodies have been found and another 18 people rescued, according to the agency.
By Wednesday, the official number of missing had jumped several times to 192 passengers.
Authorities based the figures on reports from families whose missing relatives may have been on the doomed vessel, but their accounts are difficult to verify.
If confirmed, it would be one of Indonesia's deadliest maritime disasters.
"Many people got on the boat without a ticket so it's unclear how many were on board," Muhammad Syaugi, the head of the search and rescue agency, told AFP.
Later at a press conference, Syaugi added: "There are many people who have reported their relatives missing, but whether they were on the boat or not we don't know."
The search has now turned to recovering bodies -- including those that may still be trapped inside the sunken boat.
- 'Please bring back my son' -
"We'll be here until they find my brother's body," said Nurhayati, among hundreds of grief-stricken people waiting by the shore for updates.
"We just want to see his body and take him with us."
Sobbing mother Suwarni pleaded for news of her son and his fiancé, both believed to have been on board.
"Why are the rescue teams so slow?" said the 55-year-old, who like many Indonesians goes by one name.
"I'm so disappointed -- there's no progress here. Please bring back my son."
Authorities have deployed divers and underwater vehicles, along with about 400 personnel, to search the enormous lake in an operation expected to last at least a week.
Lake Toba, popular with international and domestic tourists, fills the crater of a supervolcano that erupted tens of thousands of years ago.
It is one of the world's deepest lakes and extends some 1,145 square kilometres (440 square miles).
The rescue agency has said it plans to search as deep as 400 metres for the sunken vessel.
Images from the scene Wednesday showed rescuers covering up the bloated body of a woman who had washed ashore.
It was not clear if any foreigners were on board the ferry or what caused the disaster.
Survivor accounts said the boat began shaking as it struggled to navigate strong winds and high waves about halfway into the 40-minute trip from an island in the middle of the lake to shore.
Muslim-majority Indonesia has been celebrating the Islamic festival of Eid since Friday and millions go on holiday during the festivities, with Lake Toba among the top destinations.
The deadly disaster came just days after more than a dozen people were killed in an unrelated ferry accident in the Southeast Asian archipelago nation, where many people depend on boats to get around.
Traditional vessels -- like the one in the Lake Toba disaster -- are rarely equipped with enough life preservers and their condition can be dire.
Enforcement of safety standards also tends to be weak, underscoring Indonesia's woeful boat safety record.
In 2015 a ferry sank off the coast of the island of Sulawesi, leaving 78 dead or missing.
More than 300 people are estimated to have drowned in 2009 when a ferry sank between Sulawesi and Borneo.