A pilot error or possible technical fault most likely caused the Russian military plane to crash into the Black Sea on Sunday, Transport Minister Maxim Sokolov said on Monday, emphasising that authorities were not looking at terrorism as a cause, AP reported. The flight was heading to Latakia, Syria, after making a brief stop at Sochi for refuelling. It crashed into the sea minutes after taking off with 92 people on board, who are all feared dead.

While Sokolov said Russia did not see the need to up security measures at airports despite the Syrian connection to the crash, aviation experts have highlighted factors that suggest a terror attack. “Possible malfunctions...certainly would not have prevented the crew from reporting them,” Vitaly Andreyev, a former senior Russian air traffic controller, told news agency RIA Novosti. The fact that the debris of the Defense Ministry’s Tu-154 plane was scattered over a wide area in the sea was another noted factor indicating a terror strike.

Rescue teams, including 139 divers, recovered 11 bodies and “154 fragments” of bodies by Monday morning, said Major General Igor Konashenkov, spokesperson for the Defence Ministry, BBC reported. The bodies have been flown to Moscow to be identified. Russian President Vladimir Putin had ordered an investigation into the crash and also declared Monday a nationwide day of mourning.

The hunt is on to recover the flight recorders, but the Russian transport minister said it would be a challenge to locate them as the devices did not have radio beacons. Authorities are combing an area of 10 sq km in the Black Sea to find fragments of the aircraft and the bodies of those who were on board, which included Russia’s world famous military choir.