The head of Indonesia's National Search and Rescue Agency, Bagus Puruhito, said officials believe they identified the location of the flight data recorder and cockpit voice recorder — the so-called black boxes — because emergency signals transmitted by the devices were detected by a navy ship's sonar system.
"Hopefully we can lift the black boxes in short time to determine the cause of the crash," military chief Hadi Tjahjanto said.
Earlier Sunday, search and rescue operations resulted in parts of the plane being found in the sea at a depth of 23 meters (75 feet), leading rescuers to continue searching the area.
"We received reports from the diver team that the visibility in the water is good and clear, allowing the discovery of some parts of the plane," Tjahjanto said in a statement. "We are sure that is the point where the plane crashed."
He said the objects found included broken pieces of fuselage with aircraft registration parts.
Earlier, rescuers pulled out body parts, pieces of children's clothing and scraps of metal from the surface.
The break in the search for Sriwijaya Air Flight 182 came after the navy ship's sonar equipment detected a signal from the aircraft at a location that fit the coordinates from the last contact made by the pilots before the plane disappeared Saturday afternoon, Tjahjanto said.
The plane was en route from Jakarta to Pontianak, the capital of West Kalimantan province on Indonesia's Borneo island, on a flight that was expected to take around 90 minutes.
It was still unclear what caused it to crash. There was no sign of survivors.
"I represent the government and all Indonesians in expressing my deep condolences for this tragedy," Indonesian President Joko Widodo said.
"We are doing our best to save the victims. We pray together so that the victims can be found," he said, adding that he had asked the National Transport Safety Committee to conduct an investigation.
Fishermen in the area between Lancang and Laki islands, part of an archipelago around Thousand Islands north of Jakarta's coast, reported hearing an explosion around 2:30 p.m. Saturday.
"We heard something explode — we thought it was a bomb or a tsunami since after that we saw a big splash from the water," Solihin, who goes by one name, said by phone.
"It was raining heavily and the weather was so bad, so it was difficult to see around clearly," Solihin said. "But we saw the splash and a big wave after the loud sound. We were very shocked and saw the plane debris and the fuel around our boat."
Transportation Minister Budi Karya Sumadi said the flight was delayed for an hour before it took off at 2:36 p.m. It disappeared from radar four minutes later, after the pilot contacted air traffic control to ascend to an altitude of 29,000 feet (8,839 meters), he said.
There were 62 people on board, all of them Indonesian nationals, including three babies and seven other children. The plane was carrying 50 passengers, six working crew members and six other crew for another flight.
"Our thoughts are with the crew, passengers, and their families," Boeing said in a statement. "We are in contact with our airline customer and stand ready to support them during this difficult time."
Authorities established two crisis centers, one at Soekarno-Hatta International Airport, where the plane departed from, and one at port. Families gathered to wait for news about their loved ones.
On social media, people began circulating the flight manifesto with photos and videos of those who were listed as passengers. One video shows a woman with her children waving goodbye while walking through the airport.