Extremists from the group Islamic State, previously known as ISIS, seized the base in the northern province of Raqqa, leaving more than 85 soldiers dead and 200 more unaccounted for.The Syrian Human Rights Observatory said at least 50 of the soldiers had been executed - many of them beheaded - as horrifying footage began circulating online which appeared to show the bodies.The video, which has not been independently verified, features a voiceover by one of the militants as several decapitated heads are shown mounted on poles on top of a fence.At least two of the bodies at the Division 17 base were crucified, according to the Associated Press, which said the video appeared to be genuine. Other photographs posted on jihadist social media accounts showed fighters inside the military base in control of several tanks, trucks and ammunition boxes.In one, extremist militants raised the black flag of Islamic State above a building. In another, IS fighters are shown apparently inside Division 17's living quarters burning a portrait of Syrian President Bashar al-Assad.The head of the British-based Syrian Human Rights Observatory, Rami Abdel Rahman, told AFP hundreds of troops 'withdrew on Friday to safe places - either to nearby villages whose residents oppose IS or to nearby Brigade 93 - but the fate of some 200 remains unknown'.He added: 'Some of the executed troops were beheaded, and their bodies and severed heads put on display in Raqqa city.'More than 50 troops were summarily executed, 19 others were killed in a double suicide bombing and at least 16 more died in the assault launched on Thursday, he said.The display was intended as 'a message to the people of Raqqa, to tell them it is strong, that it isn't going anywhere, and to terrify' opponents, he added.The city has become a stronghold for Islamic State militants who have swept through Iraq and Syria, seizing civilian areas and escalating the deadly conflict in the region.They have declared an Islamic 'caliphate' throughout the region in fighting which has killed thousands of people. Syria's uprising began in the form of peaceful Arab Spring-inspired protests in March 2011 but escalated into an armed revolt when government forces launched a sweeping crackdown on dissent. The country is now in the grip of a complex civil war in which several armed groups, including Islamic extremists, are fighting government forces and rival rebels.Syria's conflict has killed at least 170,000 people, nearly a third of them civilians, according to activists. Nearly three million Syrians have fled the country.There was a victory elsewhere for the Syrian government in the central Homs region, where forces recaptured the Al-Shaar gas field which had been seized by IS a week before leading to the death of 270 troops.The Syrian army said its forces and regime paramilitaries 'killed many terrorists from the so-called Islamic State' in the recapture.The UN Commission of Inquiry on Syria has said Islamic State fighters who are accused of atrocities will be added to a list of war crimes indictees. Meanwhile a car bomb exploded in a northern Syrian town near the Turkish border yesterday, killing and wounding a number of people hours after Syrian rebels shot down a helicopter gunship over a slum in Aleppo, activists said.The Aleppo Media Center said the car bomb exploded in a vegetable market in the town of Azaz near the border with Turkey. The blast reportedly killed at least four people. (dailymail.co.uk)Bakudaily.az