KINSHASA, Congo (AP) — The United Nations said a peacekeeper in Congo was killed by an exploding shell as rebels allegedly backed by Rwanda made major advances in the country’s volatile east, taking a border crossing into Uganda and threatening a strategic town.

Panicked residents were fleeing the town of Rutshuru on Friday night amid reports that the rebels had advanced within shelling distance, according to a statement from the North Kivu Civil Society. Fears were heightened by the evacuation of U.N. and independent aid agencies, followed in the late afternoon by the retreat of Congolese army soldiers, it said.