AMMAN (Reuters) - At least 10 people were killed and a number were wounded on Thursday when a bomb blast hit a minibus carrying workers employed in a major oil installation in eastern Syria run by a U.S.-backed Kurdish group, residents of the area said.

The incident took place near the town of Al-Shahil in the southeast of oil-rich Deir al-Zor province that borders Iraq, in an area under the control of the Kurdish-led Syrian Democratic Forces (SDF) that are backed by Washington.

It was not known who carried out the attack. It came as the SDF presses on with efforts to retake the last small area of territory held in Syria by Islamic State.

Activists with relatives in the area said many of the young men in the blown-up minibus had come from work in the nearby al-Omar field, one of Syria’s largest oil fields.

Video on social media purportedly showed bodies lying on the ground following the attack. A source in the area said at least two SDF fighters were among those killed.

Residents say attacks have increased in recent months in SDF-controlled areas. The group has a swathe of territory in northeast Syria on the border with Turkey, down the Euphrates River toward the border with Iraq.