Authorities said they determined the location of the crash site and black boxes of a Boeing 737-500 on Sunday, a day after the aircraft crashed into the Java Sea with 62 people on board shortly after taking off from Indonesia’s capital.

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.

“We have determined the position of the plane’s black boxes from two signals emitted by the devices,” military chief Hadi Tjahjanto said. “Hopefully, we can lift the black boxes in short time to determine the cause of the crash.” Earlier on Sunday, search-and-rescue operations resulted in parts of the plane being found in the sea at a depth of 23 metres (75 feet), leading rescuers to continue searching the area.