A boat of Russian Emergencies Ministry sails near the crash site of a Russian military Tu-154 plane, which crashed into the Black Sea on its way to Syria on Sunday, in the Black Sea resort city of Sochi, Russia, Dec. 26, 2016. REUTERS/Maxim Shemetov

UPDATE: 4:43 a.m. EST — The examination of fragments from the crashed Russian Tu-154 plane show no signs indicating an explosion or a fire on board the jet before it crashed into the Black sea, a security source told TASS on Tuesday.

"The four main versions are an engine being hit by a foreign object, substandard fuel that caused the loss of thrust on and eventually stopped the engines, the pilot’s mistake and the plane’s technical failure," Russia’s Federal Security Service earlier said.

Meanwhile, another local media cited an expert who said a bird may have hit the aircraft’s engine, causing the crash.

UPDATE: 12:45 a.m. EST — Russian news agency TASS reported Tuesday that divers found the black box located in the fin section of the Tu-154 aircraft in the Black Sea, adding that two other flight recorders that are located in the tail section of the aircraft were yet to be found.

Original story:

The black box of Russian Tu-154 plane has been detected in the Black Sea, sources told local media Tuesday. The military plane, which was carrying 92 people, crashed Sunday while on its way from Sochi to Latakia province in western Syria.

According to local reports, the flight recorder will be extracted from the water and analyzed to determine the cause of the crash. Earlier, the commander-in-chief of Russian Aerospace Forces said the flight recorders of the plane were placed in the fin of the Tu-154 jet and suffered minimal damage.

Divers and submersibles have so far recovered at least four pieces of debris, 11 bodies and 86 body fragments from the sea floor. Most of the bodies found so far were taken to Moscow on Monday. Russia expanded its search operation Monday for the remains of the plane but strong currents and deep water were reportedly complicating the efforts. Russian news agency TASS reported one of the 11 bodies recovered so far belongs to the pilot in command, Roman Volkov.

"When large fuselage fragments were lifted, one more body was found. When lifted the body was identified as the plane’s pilot in command Roman Volkov, judging by the insignia," a source reportedly said.

Russia's transport ministry said Monday that human error or mechanical fault were likely responsible for the downing of the jet.

Kremlin spokesman Dmitry Peskov also said military investigators were considering all theories, but that the version it may have been "a terrorist act" was "nowhere near the top of the list." The four potential causes being considered for the crash were a foreign object entering the engine, poor quality fuel causing engine failure, human error on the part of the pilot or a yet unknown technical issue.

Russian President Vladimir Putin directed Prime Minister Dmitry Medvedev to establish and head a government commission for an investigation into the incident. The country’s investigative committee launched a criminal case into "the violation of rules of flights safety or preparation for them."