Indonesia has launched a sea and air search effort. The rescue operation, which includes 11 navy ships, is set to continue throughout the night.
Tracking showed the path of flight SJ182 ending off the coast just north of Jakarta after the plane abruptly lost altitude.
The plane took off from Jakarta’s Soekarno-Hatta Airport at about 2:36 p.m (7:36 UTC)
The flight, which was bound for the city of Pontianak, northwest of Jakarta, last made contact around 2:40 p.m.
There were 62 people, including children, listed on an unconfirmed manifest of those on board, reported Indonesian newspaper Republika.
There were two pilots and four cabin crew on board, according to Indonesia’s iNews.
The plane lost more than 3,000 meters (10,000 feet) of altitude in less than a minute, reported flight tracker website FlightRadar24.
Bambang Suryo Aji, a senior official at the country’s national search and rescue agency, told AFP that the plane had likely gone down.
“We deployed our team, boats and sea riders to the location suspected to be where it went down after losing contact,” the official said.
The Regent of the Thousand Islands chain said he had information that “something fell and exploded on Laki island,” in comments to Indonesian newspaper Merdeka.
Previously, the Soekarno-Hatta Airport Branch Communications Manager Haerul Anwar said that the Sriwijaya Air plane had lost contact around Lancang Island — part of the Thousand Islands chain.
Unconfirmed images of small debris fished from the water were broadcast by local media.
“We found some cables, a piece of jeans, and pieces of metal on the water,” CNN Indonesia quoted security official Zulkifli as saying.
A patrol boat from the Ministry of Transportation found possible human body parts and oil near to the reported site of a crash, reported local news outlet Kompas.
Indonesian TV footage showed relatives and friends of those aboard the plane weeping, praying and hugging each other as they waited for information at airports in Jakarta and Pontianak.
Sriwijaya Air, an Indonesian airline, said in a statement it is still gathering more detailed information regarding the flight before it can make a fuller statement.
A Boeing spokeswoman said, “We are aware of media reports from Jakarta, and are closely monitoring the situation. We are working to gather more information.”
Boeing has been plagued with problems ever since manufacturing the infamous 737 MAX modelthat was involved in two deadly crashes in less than a year.
In October 2018, a total of 189 people were killed when a Lion Air Boeing 737 MAX jet slammed into the Java Sea about 12 minutes after take-off from Jakarta on a routine one-hour flight.
In March 2019, an Ethiopian Airlines Flight 302 crashedafter taking off from Addis Ababa. All 157 people on board died.
The model was grounded and the company was Boeing was fined $2.5 billion (€2.04 billion) over claims it defrauded regulators overseeing the 737 MAX model.
The plane that lost contact on Saturday is a much older model. The nearly 27-year-old aircraft did not use the new, questionable autopilot systems built into the current-generation 737 MAX planes, DW reported.