A passenger jet has reportedly crashed in southern Russia.
According to Reuters Russia's southern regional emergency center confirmed to CNN that the Boeing 738 jet crashed as it was landing at the Rostov On Don airport.
Local media reports suggest 55 people were on board when the plane crashed.
Russia will complete the withdrawal of most of its military forces from Syria "in two to three days", a Russian air force official has said in an interview with state-run media.
President Vladimir Putin ordered the pullout of forces from the country on Monday.
He emphasised that the Russian airbase in Hemeimeem in Syria's coastal province of Latakia and a naval facility in the Syrian port of Tartous will continue to operate.
The Syrian opposition said Russia's partial withdrawal of forces could pave the way for an end to the five years of fighting in the country.
But spokesman Salim al-Muslat told reporters officials in Moscow had not directly informed them of Russian President Vladimir Putin's decision.
Mr al-Muslat said the withdrawal of troops could help bring about an end to Syrian President Bashar Assad's "dictatorship and his crimes".
Foreign Secretary Philip Hammond has said Russia should be judged on actions not words as he awaited confirmation of its partial withdrawal of forces from Syria.
Mr Hammond told the Commons the international community had not received "independent evidence" of the downscaling of Russian forces
He said he would be "delighted" if the reports were verified but said no members of the International Syria Support Group were given advance notice of Mr Putin's surprise announcement and urged caution.
No one would be more delighted than me if, after five months of relentless bombing, Russia is genuinely winding down its military support to the brutal Assad regime.
But, as in all matters related to Russia, it is the actions rather than the words that count. We shall be watching carefully over the coming days to see if the potential promise of this announcement turns into reality.
The Russian air force will continue striking targets in Syria linked to Islamic State and other groups as it is "still early to talk about victory over terrorism", a Russian minister has said as a first wave of departing jets land at home.
The Kremlin's chief-of-staff separately confirmed Russia will keep its most advanced air defence system in Syria, which has a range of almost 250 miles, despite withdrawing the bulk of the nation's forces.
Video shows Russian planes taking off and flying home from Syria base
Deputy defence minister Nikolai Pankov was meanwhile quoted by the RIA news agency as saying a "real chance has emerged" to end the conflict through the resumed Geneva peace talks.
But despite speaking at a "mission accomplished" ceremony he guarded against snap conclusions from Russia's partial withdrawal of forces.
Certain positive results have been achieved. A real chance has emerged to put an end to this long-running standoff. But it is still early to talk about victory over terrorism. The Russian aviation group has the task to continue carrying out strikes on terrorist facilities.
The first group of Russian planes have flown out of their Syria base after Russian president Vladimir Putin announced a surprise partial withdrawal of military equipment and personnel from the war-torn country.
Russia's defence ministry confirmed a group including Sukhoi-34 fighter-bombers had left the Hmeymim air base after Russian state television showed air base personnel loading transport aircraft for return.
The ministry said each group will be led home by either a Tupolev-154 passenger plane or an Ilyushin-76 transport aircraft carrying engineers, technical personnel, and cargo.
Mr Putin has not specified how many planes and troops will remain but said a Russian airbase in Hemeimeem in Syria's coastal province of Latakia and a naval facility in the Syrian port of Tartous will continue to operate.
Russia has started to withdraw military equipment and personnel from Syria, the AFP newswire has reported.
Russia’s sudden withdrawal from Syria was a bolt from the blue which should bolster peace talks getting underway in Geneva, reports ITV News correspondent Juliet Bremner.
Moscow has conducted 9,000 sorties in the war-torn country since it began a military intervention insupport of president Bashar al-Assad last September.
The onslaught has helped government forces regain momentum in a brutal civil war - and it has also transformed President Putin’s standing on the international stage.
Ithas come at a heavy price in terms of human lives - 4,400 have been killed, according to Syrian Observatory of Human Rights, including more than 1,700 civilians.
While it’s not clear why Putin has chosen to withdraw most of his forces now, the removal of Assad’s main outside support should boost efforts to reach a permanent political solution to the crisis.
President Obama has welcomed the reduction in violence following Russian's announcement it would partially withdraw from the country.
In a phone call with Putin, the US president stressed continuing fighting by Syrian regime forces risked undermining the truce and the UN-led political process.
He also emphasised the need for combined Russian-separatist forces to implement a ceasefire in Ukraine.
The Syrian presidency has said Russia's decision to withdraw from the country was "coordinated" and had been planned "for some time".
In a statement, it added the pull out did not reflect a difference between the two countries.
"The whole subject happened in complete coordination between the Russian and Syrian sides."