The situation in Congo has been a source of much tension
A number of people have been killed in north-eastern Democratic Republic (DR) of Congo in a day of fighting and looting.
Thousands of residents are spending the night in buildings protected by United Nations peacekeepers.
Clashes between rival ethnic militias broke out in the town of Bunia following the withdrawal of Ugandan forces.
The violence came as the presidents of Uganda and Rwanda met in London to discuss - among other issues - peace in the DR Congo where they have both supported rival rebel groups.
Hundreds of militia fighters - some children - roamed Bunia's streets on Thursday, some armed with machetes and spears, others with guns.
Reports say there have been heavy casualties and widespread looting and that thousands of people have fled the town.
A plane carrying the Congolese Human Rights Minister, Ntumba Luaba, was hit by gunfire near the town's airport, forcing the pilot to make an emergency landing.
Residents of Bunia said that as darkness fell on Thursday, the fighting died down.
The Ituri region has seen several massacres in recent months carried out by rival ethnic groups, which include the Lendu and Hema.
BBC correspondent Mark Dummett in the capital, Kinshasa, says the most recent fighting was the scenario everyone feared once the Ugandans withdrew.
He says the UN has only a small presence in the town, although several hundred peacekeepers are expected by the end of next week.
DR CONGO'S WAR
Seven foreign armies
At least 2 million dead
Disease and abuses widespread
The head of the United Nations mission in DR Congo, Amos Namanga Ngongi, told the BBC that he does not have enough men to stop the bloodshed.
In London on Thursday, Uganda's President Yoweri Museveni and Rwandan President Paul Kagame agreed to fully support the implementation of the peace process in DR Congo.
Both countries have been heavily involved in the fighting there which has cost hundreds of thousands of lives.
Their forces invaded Congo as allies in 1998, but ended up supporting rival rebel groups.
Threat of war
Tensions flared earlier this year when Uganda redeployed its army in Ituri.
The Rwandans complained that this was a breach of the agreement which led to the withdrawal of thousands of their troops.
They threatened to redeploy and, according to some unconfirmed reports, some Rwandan soldiers did indeed cross back into DR Congo.
The BBC's correspondent in the region, Ishbel Matheson, says the fact the UK Government is taking the trouble to mediate indicates just how seriously the rift between these African neighbours is seen internationally.
A war between Rwanda and Uganda would spell disaster for an already turbulent region, she says.