A Lion Air flight with 188 people on board crashed into the sea just minutes after taking off from Indonesia's capital on Monday.
Indonesia's disaster agency posted photos online of a crushed smartphone, books, bags and parts of the aircraft fuselage that had been collected by search and rescue vessels that have converged on the area.
Spokesman Sutopo Purwo Nugroho said the aircraft, on a 1 hour and 10 minute flight to Pangkal Pinang on an island chain off Sumatra, was carrying 181 passengers, including one child and two babies, and seven crew members.
Indonesian TV broadcast pictures of a fuel slick and debris field.
The National Search and Rescue Agency said the flight ended in waters off West Java that are 30 to 35 meters (98 to 115 feet) deep.
The agency's chief Muhammad Syaugi told a news conference that divers are trying to locate the wreckage.
The Boeing 737-800 plane departed Jakarta, about 6.20 a.m. for Pangkal Pinang. Data for Flight 610 on aircraft tracking website FlightAware ends just a few minutes following takeoff.
Indonesian TV showed dozens of people waiting anxiously outside the Pangkal Pinang airport and officials bringing out plastic chairs.
The crash is the worst airline disaster in Indonesia since an AirAsia flight plunged into the sea in December 2014, killing all 162 on board.
A report to the Jakarta Search and Rescue Office cited the crew of a tug boat which had reported seeing a Lion Air flight falling from the sky.
A telegram from the National Search and Rescue Agency to the air force has requested assistance with the search.
Lion Air is one of Indonesia's youngest and biggest airlines, flying to dozens of domestic and international destinations.
In 2013, one of its Boeing 737-800 jets missed the runway while landing on the resort island of Bali, crashing into the sea without causing any fatalities among the 108 people on board.