|DR Congo: Bunagana residents flee M23 clashes to Uganda|
More than 4,000 people have fled at night from a border town into Uganda after rival rebel factions fought in the Democratic Republic of Congo.
The violence followed the sacking of the political leader of the M23 rebel group, Jean-Marie Runiga, on Thursday.
Mr Runiga is allied to Bosco Ntaganda, a rebel commander wanted by the International Criminal Court on war crimes charges.
Some 800,000 people have been displaced since the M23 rebellion began in 2012.
On Sunday, regional African leaders signed a UN-brokered accord to end the conflict.
The UN refugee agency in Uganda told the BBC about 4,500 people crossed the border overnight.
"It started at around midnight and we can still hear the bullets and bombs," Damien Batimaha, a local community leader in the border town of Bunagana, told Reuters news agency.
"Most of the town has fled. I'm at home but my family has already left," he said.
The town is under the control of fighters loyal to the M23's main leader, Brig Gen Sultani Makenga.
Rebel spokesman Col Vianney Kazarama told the BBC's Great Lakes Service that the M23 fighters were ambushed as they made their way to Rumangabo, a military base about 50km (31 miles) north of Goma.
They were attacked by men loyal to Gen Ntaganda using heavy weaponry. There were many casualties on both sides, the spokesman said.
The second attack came at midnight on the the M23 headquarters near Bunagana.
Col Kazarama said he believed the attack was prompted by the peace accord signed in Addis Ababa, which mentioned arrest warrants - and Gen Ntaganda fears he will be handed over to The Hague.
The M23 - mostly made up of fighters from the Tutsi minority group who deserted from the army - launched a rebellion against the DR Congo government 11 months ago, briefly seizing Goma, the main city in the east, in November.
The rebellion was founded by Gen Ntaganda, who was an officer in the Rwandan army before he left to join a rebel movement in DR Congo.
In a statement signed by Gen Makenga on Thursday, Mr Runiga was accused of treason because of "financial embezzlement, divisions, ethnic hatred, deceit and political immaturity".
Rwanda and Uganda have denied UN allegations that they are backing the group.