A Lion Air Boeing 737 passenger plane has come down from Jakarta after take-off, say Indonesian officials.
She lost contact with the ground control a few minutes after launch when she crossed the sea.
It was not immediately clear how many people were aboard the aircraft, a brand new Boeing 737 MAX 8.
Yusuf Latif, a spokesman for the National Search and Rescue Service, told reporters: "It has been confirmed that it is crashed. "
Airline Chief Executive Edward Sirait earlier told Reuters," We can not comment at the moment, we're trying to gather all the information and data. "
Indonesian media cited a port official at Tanjung Priok as a tug had reported plane crashes in the water.
Suyadi, who uses only one name like many Indonesians, said other ships made their way to the construction site.
JT-610 flight departed Monday morning at 06:20 local time from Jakarta (Sunday at 23:30 GMT). After a short flight, it should arrive in Pangkal Pinang one hour later.
The aircraft is said to have been a Boeing 737 MAX 8, a model that has only been in use since 2016. Flightradar24, the airline tracking website, said the plane had been delivered to Lion Air in August.
Aviation Consultant Gerry Soejatman told the BBC The MAX 8 has had problems since its introduction, including the problems of maintaining a level flight.
Indonesia, a vast archipelago, relies heavily on air travel, but many of its airlines have a poor safety record.
Lion Air is a low cost airline based in the country. In 2013, Lion Air Flight 904 crashed into the sea landing at Bali Ngurah Rai International Airport. All 108 people on board survived. In 2004, a 538 Lion Air Flight crashed from Jakarta landing in Solo City, killing 25 people.