The Democratic Republic of Congo's army on Thursday accused a notorious rebel group of killing 50 civilians and of breaching a truce in fighting with the armed forces.
In a statement, spokesman General Sylvain Ekenge said the M23 group was "carrying out massacres... the most recent of which is that of 50 Congolese civilians, heinously murdered on Tuesday in Kishishe," a village north of the eastern city of Goma.
The sources said fighting resumed Thursday at Kirima, about 10 kilometers from the town of Kibirizi.
"Fighting resumed this morning between the FARDC and the M23," said Paul Lutibahwa, head of civil society groups for the Bambo region. The FARDC stands for the armed forces of the Democratic Republic of Congo (DRC).
"The rebels have crossed the bridge, heading for Kibirizi... there's panic," he said.
Juson Kaniki, a representative of civil groups in Kibirizi, confirmed that "people are starting to flee" in fear of the rebels' arrival.
A security official, speaking on condition of anonymity, accused the M23 of having breached the ceasefire and "carrying on looting and fighting."
A DRC army officer, who also asked not to be identified, said, "The fighting is heavy -- we are using heavy artillery."
The M23's military spokesman, Willy Ngoma, contacted by AFP, confirmed that there was fighting with the army.
Until Thursday's violence, there had been no fighting between government forces and the M23, although the rebels had clashed with local militia, especially in the Bambo area, where civilian casualties were reported.
Scores of armed groups roam eastern DRC, making it one of Africa's most violent regions.
Many are legacies of two wars before the turn of the century that sucked in countries from the region and left millions dead.