BEIRUT — The Islamic State group has released most of the 300 cement workers it abducted near Damascus after questioning them to find out who were Muslims and killing four who were members of the minority Druze sect, a Syrian opposition monitoring group and a news agency linked to the extremists reported Saturday.

The reports came two days after the group, also known as ISIS, abducted the cement workers and contractors from al-Badia Cement Company in Dumeir, about 28 miles northeast of the capital, after a surprise attack on government forces.

The Britain-based Syrian Observatory for Human Rights said all those abducted have been released except for 30 people who were guards at the cement factory. It said the fate of the 30 is unknown.

The ISIS-affiliated Aamaq news agency said most of the 300 were released after questioning to determine their religion and whether they support the government. It said four workers who belonged to the minority Druze sect were killed and 20 pro-government gunmen are still being held.

The Druze, a 10th-century offshoot of Shiite Islam, made up about 5 percent of Syria’s pre-war population of 23 million people. Lebanon and Israel also have large Druze communities.

ISIS, a Sunni Muslim extremist group, considers all Shiites to be heretics deserving death.

Aamaq also released a video from inside the cement plant, about 28 miles northeast of Damascus, showing trucks and bulldozers in the sprawling facility. Some fighters could be seen inside.

Government forces and insurgents meanwhile clashed near Handarat, just north of the northern city of Aleppo, Syria’s largest, activists said.