A passenger plane with an estimated 62 people on board has gone missing shortly after take-off from the Indonesian capital Jakarta
The Sriwijaya Air Boeing 737 lost contact en route to Pontianak in West Kalimantan province, officials said.
Flight tracking website Flightradar24.com said the aircraft had lost more than 3,000m (10,000ft) in altitude in less than a minute.
Witnesses said they had seen and heard at least one explosion.
Fisherman Solihin, who goes by one name, told the BBC Indonesian service he had witnessed a crash and his captain decided to return to land.
“The plane fell like lightning into the sea and exploded in the water,” he said.
“It was pretty close to us, the shards of a kind of plywood almost hit my ship.”
A number of residents of an island near where the plane disappeared told the BBC they had found objects they thought were from the plane.
The transport ministry said search and rescue efforts were under way.
It said last contact with the plane, with the call sign SJY182, was made at 14:40 local time (07:40 GMT).
There were thought to be 56 passengers and six crew on board, though the plane has a capacity of 130.
The usual flight time to Pontianak, in the west of the island of Borneo, is an hour-and-a-half.
