Kurdish fighters seize Syrian border post from Islamists BEIRUT (Reuters) - Kurdish militants seized a Syrian border post on the frontier with Iraq early on Saturday, fighters and monitors said, after three days of clashes with an al Qaeda-linked group which had held the crossing since March. The armed Kurdish group YPG told Reuters fighting carried on through the morning and a senior security official on the Iraqi side of the crossing said he could hear gunshots, mortar fire and shelling. The Yarubiya post and surrounding areas in the northeast were taken from the Islamic State of Iraq and the Levant rebel group, who had seized it from the army, The Syrian Observatory for Human Rights said. Ethnic Kurds in Syria have a complex role in nearly three years of conflict that started when President Bashar al-Assad cracked down on a pro-democracy uprising. The ensuing war has pitted Sunni Muslims against Assad's Alawite minority and different Kurdish militia have fought on both sides, normally over territory or power disputes. YPG spokesman Redur Xelil told Reuters Kurdish areas in Syria were blockaded by Islamist groups on one side, Turkish forces on the other and the closed border with Iraqi Kurdistan. But he said it was "too soon to talk about using the crossing." Forty people died when a car bomb exploded outside a mosque in Wadi Barada in Damascus province on Friday, said the anti-Assad Observatory, which verifies reports through a network of sources around Syria. State news agency SANA said many "terrorists" - a term it uses for those fighting Assad - were also killed in the explosion and quoted a witness who said the mosque's two entrances collapsed when the bomber struck before the end of Friday prayers. State TV said on Friday Abu Mohammad al-Golani, leader of Jabhat al-Nusra, a rebel group that has claimed responsibility for several suicide bombings, had been killed. Fighters from the Islamist group told Reuters Golani was alive. The Syrian conflict has killed more than 100,000 people, according to the United Nations. Reporting by Oliver Holmes in Beirut, Isabel Coles in Arbil and Ziad al-Sinjary in Mosul; Editing by Andrew Heavens