Indonesian authorities were questioning more than 70 mostly Afghan asylum seekers bound for Australia after their boat was hit by a powerful wave, forcing them to swim to shore, officials said.
Community members of Wonogoro beach on the eastern coast of Java island reported seeing scores of people wash up onto the shore late Friday night, some beginning to run away, Malang police chief Rinto Djatmono told AFP.
"We found 43 last night including three children and one woman. They are being questioned by the Malang city immigration office and they are all in a healthy condition," Djatmono said.
Police detained another 30 late Saturday morning and are still searching for more believed to be missing.
Search and rescue officials told AFP they were not searching the sea.
Some of the asylum seekers had already been processed by the United Nations High Commissioner for Refugees, Djatmono said.
Officials have had trouble communicating with the asylum seekers, but have been told there were between 83 and 100 on the boat.
"From what they've told us, we know their engine had broken down two days earlier, and a strong wave hit the boat and destroyed the vessel," Djatmono said, adding it was unclear how far they had swum.
Last week, Indonesian authorities said they believed dozens of mostly Afghan asylum seekers had fled a leaky boat with malfunctioning engines found on Lombok island, near the resort island of Bali.
Those asylum seekers have not been found, and police have made no connection between the two cases.
Indonesia is a common transit point for asylum seekers trying to reach Australia's Christmas Island, which is closer to Java than mainland Australia, and many of the overloaded rickety boats do not make it.
In December, a boat carrying around 250 mostly Afghan and Iranian asylum seekers sank in Indonesian waters on its way to Christmas Island, with only 47 surviving.