There was gunfire Tuesday in the eastern Democratic Republic of Congo city of Goma, as the United Nations warned of a worrying humanitarian situation amid clashes between Congolese soldiers and Rwandan-backed rebels who attacked the area and claimed to be in control.

"Active zones of combat have spread to all quarters of the city, all the neighborhoods of the city," Lemarquis, the deputy U.N. envoy and top U.N. aid official in the DRC, told reporters in New York via video from Kinshasa.

Their fury is focused on Rwandan President Paul Kagame, who they accuse of backing the rebels - an accusation long made by the UN. To put it bluntly, a group of UN experts maintains the Rwandan army is in "de facto control of M23 operations",