Sudanese paramilitary forces seized a key military base in the army’s last stronghold in the embattled western Darfur region, activists and aid groups said Monday, in a significant blow to the military in a war that has gripped the country since 2023.

Medical groups reported dozens of civilians killed and health infrastructure destroyed as fighting raged on between the two sides in el-Fasher, the provincial capital of North Darfur. There were no definitive numbers on the casualties. Over 26,000 people have been forced to flee their homes, according to the United Nations.

The city has been a focal point of the conflict for over a year, with widespread devastation and displacement — a place where hundreds of thousands of people have become trapped.

The war started in April 2023 when simmering tension between the military and the paramilitary Rapid Support Forces, or RSF, exploded into open fighting in the capital, Khartoum, and elsewhere in the northeastern African country.

El-Fasher was the Sudanese military’s last stronghold in Darfur and its fall to the RSF could mark a dangerous point in the war and herald another split of the country more than a decade after the creation of South Sudan.