Nine United Nations peacekeepers in eastern Congo sustained injuries during fighting with the M23 armed group, the U.N. said, as the rebels close in on Goma.

Congolese troops pushed back an attempted overnight advance by Rwanda-backed rebels on the eastern city of Goma, two Congolese army sources said on Saturday, after the sound of nearby heavy bombardment rocked the city in the early hours.

Many Congolese see the rebel advance as an invasion of their country by a foreign power in an attempt to seize land and Congo’s valuable rare minerals.