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.

The president of crisis-hit Democratic Republic of Congo was set to meet his Rwandan counterpart at an emergency summit on Wednesday, as fighters backed by Kigali appeared on the brink of seizing the key city of Goma.

"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.