A Turkish soldier was shot dead at the border with Syria in southern Turkey by an unidentified assailant who opened fire from Syrian territory, the Dogan news agency reported Thursday. The shooting occurred in the Reyhanli district of Turkey's Hatay province. Dogan gave no further details and the shooting could not immediately be confirmed. One soldier was killed and another is still missing after a cross-border shooting with ISIS fighters last week near the Turkish town of Kilis, further east. Turkey's Hurriyet newspaper said Saturday that the missing soldier had been seen in a hospital run by ISIS. If confirmed, his capture could become a major challenge for Turkey, after it stepped up military action against Islamic State in July, opening its air bases to U.S.-led coalition war planes and launching air strikes. Late last month, ISIS released a video accusing Turkish President Tayyip Erdogan of "treachery," and urged Turks to rise up against him.