The Islamic State (IS) group began releasing some of 300 cement plant workers taken captive northeast of Damascus earlier this week, a monitoring group said on April 8.
Local municipal officers secured an agreement with IS to release 170 workers the militants had been holding since April 6, the Syrian Observatory for Human Rights said.
IS seized the workers from the Al-Badia cement factory after launching an attack on Syrian government forces in the area where the plant is located, near the town of Dumeir.
Syrian state television said IS had kidnapped 300 workers and contractors. The Observatory said 140 workers had fled before the fighters arrived.
IS's Amaq news agency said on April 8 that the group freed nearly 300 workers, but had executed four of them for being Druze, an offshoot of Islam that IS considers heretical.
It said IS would not free 20 men accused of belonging to a pro-government militia.