SURABAYA, Indonesia — SURABAYA, Indonesia (AP) — Indonesian rescuers were searching for possible missing passengers Monday after rescuing 229 people from a ferry that caught fire the previous day in waters off the main island of Java, leaving at least five people dead.

The Mutiara Sentosa 2 ferry was traveling from Indonesia’s second-largest city of Surabaya in East Java to the city of Makassar in South Sulawesi, and initial reports said it was carrying 232 passengers and 39 crew members, based on the ship’s manifest, when the fire broke out between 6 a.m. and 7 a.m. in waters off Sumenep regency.

However, by Monday morning officials said many more people were aboard than listed, and that the number of people still missing was unclear after 229 people were rescued and five bodies recovered. Officials are relying on reports from the families of victims and survivors in an attempt to determine the number of those missing.

It is common in Indonesia for the number of passengers on a boat or ferry to differ from the manifest. Such discrepancies can reflect overcrowding and complicate search and rescue efforts, said Nanang Sigit, who heads the Surabaya Search and Rescue Office.

The cause of the fire was not immediately known and remained under investigation.

The vessel was also loaded with 180 vehicles, mostly trucks, and an excavator.

Ahmad Abdul Karim, one of the survivors, said the fire appeared to have started from a truck on the lower vehicle deck.

“Fanned by the wind, the flames spread extremely quickly,” Karim said, “In less than 30 minutes, everyone had been instructed to move to the bow of the ferry.”

Search and rescue teams dispatched a rescue boat from Surabaya to the scene, about 35 kilometers (22 miles) north of Buruan Sapudi island in the Sumenep regency. Indonesian navy ships also assisted along with a number of passing vessels near the location of the incident.

The ferry was built in Japan in 1992 and operated there before being sold to Indonesia in 2015. With a length of 160 meters (525 feet), it can accommodate 689 passengers and 49 crew, along with up to 181 vehicles.

The Mutiara Sentosa 2 serves the Surabaya-Makassar route, a voyage that typically takes around 40 hours and is primarily used by domestic travelers and cargo transport between the islands of Java and Sulawesi.

Indonesia is an archipelago of more than 17,000 islands where ferries are a common method of travel. Disasters occur regularly, with weak safety enforcement often blamed.

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Associated Press journalists Niniek Karmini and Edna Tarigan in Jakarta, Indonesia, contributed to this report.