BARDARASH, Iraq (AP) — Humanitarian groups in northeastern Syria are scrambling to provide aid to hundreds of thousands of people as rapidly shifting battle lines make it increasingly difficult to reach them.

Nearly all foreign aid workers have been evacuated because of security concerns, and there are fears that local staff could face reprisals, either at the hands of Turkish-led forces pushing in from the north or Syrian troops fanning out across territory held by the embattled Kurds.

The front lines are being rapidly redrawn as more than 160,000 people flee the fighting, including many who were displaced by earlier battles in Syria's eight-year civil war. The offensive has created a new refugee crisis in a region where some 1.6 million people already rely on humanitarian aid.