Russia's transport minister and a team of high-level investigators have begun assisting Egyptian authorities determine what caused a Russian airliner to crash in the Sinai Peninsula, killing all 224 people on board.
As the investigation begins, St Petersburg, the flight's destination, was at the centre of a national day of mourning in Russia. Flags were at half-mast and residents called the crash "terrifying."
The Airbus A321, operated by Russian airline Kogalymavia under the brand name Metrojet, was flying from the Red Sea resort of Sharm el-Sheikh when it went down in central Sinai soon after daybreak on Saturday. It crashed into a mountainous area shortly after losing radar contact near cruising altitude.
On Sunday, a report in the Wall Street Journal said that debris from the tail section was found separate from the rest of the fuselage, which suggests it may have split off midair, people familiar with the investigation told the publication.
So far, at least 163 bodies have been recovered and transported to various hospitals including Zeinhom morgue in Cairo, according to a cabinet statement.
Search efforts resumed at the crash site early on Sunday morning and Russian experts were already at the site helping to recover bodies and begin investigations into the cause. Russian investigators had already visited the morgue, a security source said.
Emergency services and aviation specialists had searched the wreckage on Saturday for any clues to the crash. Both black boxes had been recovered, Egypt's civil aviation minister said.
Judicial and ministry sources told Reuters that Egyptian and Russian investigators would begin examining the contents of the black boxes within hours.
The Russian flag could be seen flying at half-mast over the Russian embassy in Cairo on Sunday morning.
A militant group affiliated to Islamic State in Egypt said in a statement that it had brought down the plane "in response to Russian airstrikes that killed hundreds of Muslims on Syrian land", but Russia's Transport Minister Maxim Sokolov told Interfax news agency the claim "can't be considered accurate".
Russia, an ally of Syrian President Bashar al-Assad, launched air raids against opposition groups in Syria, including Islamic State, on Sept. 30.
Islamic State, the ultra-hardline group that controls large swathes of Iraq and Syria, has called for a holy war against both Russia and the United States in response to airstrikes on its fighters in Syria.
But militants in the Sinai area are not believed to have missiles capable of hitting a plane at 30,000 feet. Islamic State websites have in the past claimed responsibility for actions that have not been conclusively attributed to them. Flight KGL9268 was flying at 31,000 feet when it disappeared from radar screens, according to reports.
Officials say there is no evidence to suggest that a bomb could have brought down the plane.
Also on Sunday, Russian news agency RIA quoted the Volga region's transport prosecutors as saying that the quality of the fuel used by the Russian airliner met all necessary requirements.
Meanwhile, in St Petersburg, thoughts were with the victims, most of whom were Russian. There are reportedly 17 children among the dead.
A resident called Artem told Reuters the sight on television of passengers' grieving relatives had "hit me in the heart."
"I have a desire not to fly anywhere ... Yes, this happens, we also fly to vacations, we do, but now we are afraid," he said.