Attacks on Ebola treatment centers in eastern Democratic Republic of Congo underscore the growing challenges authorities face, including rising community resistance, as they work to contain an outbreak declared a global health emergency.

Congolese authorities said Sunday that suspected cases have surpassed 900 in the country’s east, mostly in Ituri Province, the epicenter of the outbreak. Later that night, angry young men stormed an Ebola treatment hospital in Mongbwalu, according to the hospital director.

The attackers were demanding the release of two relatives’ bodies, said Dr. Richard Lokudu. Medical staff evacuated patients as gunfire erupted nearby, and it was not immediately clear whether anyone was injured.

The assault, along with arson attacks on two health centers last week in the outbreak’s core region, underscores rising tensions in an area long destabilized by armed rebel violence, mass displacement, weak governance and aid cuts that have strained already fragile health services.

“A devastating set of emergencies are converging,” said the Physicians for Human Rights nonprofit.