BEIRUT (AP) — Activists say Islamic State fighters have captured 21 Kurdish villages over the past 24 hours in northern Syria near the Turkish border.

The Islamic State group and Kurdish militias have been locked in a fierce fight in several pockets of northern Syria where large Kurdish populations reside. Momentum in the fight has swung back and forth. Earlier this week, Kurdish fighters captured 14 villages from the Islamic State in other parts of Syria.

But the Britain-based Syrian Observatory for Human Rights says Islamic State militants appeared to gain the upper hand on Wednesday. The Observatory says both sides suffered casualties, but Kurdish civilians have begun to flee their villages for fear that the Islamic State group “will commit massacres against civilians.”

Syria’s powerful Kurdish Democratic Union Party says the Kurdish fighters withdrew or lost up to 20 villages in the region and evacuated civilians with them.

The Dogan News Agency says nearly 3,000 people trying to flee to Turkey have gathered near the border asking to be allow to cross to stay with relatives on the Turkish side.

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