Paramilitary forces in Sudan's Darfur have mutinied, the interior ministry said on Sunday, as a United States diplomat expressed concern that security in the western region is worsening.
"A small group from the Central Reserve Police started a mutiny," the ministry said in a statement carried by the official SUNA news agency.
It said the mutineers were from the West Darfur unit of the special police and were based in the state capital El Geneina near the Chadian border.
They "started firing their guns in the air", panicking residents, before fleeing southwest, the ministry said.
It added that there were no casualties and Sudan's army was in pursuit after the incident, which is unusual despite a decade of unrest in Darfur.
SUNA said the mutineers "withdrew from their compound and took with them four Land Cruisers with weapons, and some food".
The town is now calm, SUNA said.
The Central Reserve is one of the government forces used against rebels who have been fighting in Darfur since 2003 against the Arab-dominated regime in Khartoum.
Darfuri members of the Reserve formerly belonged to the Janjaweed, a government-backed militia which shocked the world with atrocities against ethnic minority civilians suspected of supporting the rebels.
More recently the Central Reserve have been implicated in other abuses.
Last week the Salamat tribe accused Central Reserve members of joining fighting in Rahad el Berdi near Umm Dukhun, more than 200 kilometres (120 miles) south of El Geneina.
At least 18 people were killed in clashes between the Misseriya and Salamat tribes around Umm Dukhun, a tribal leader said.
A United Nations panel of experts reported in February that eyewitnesses and victims blamed elements of the Central Reserve and other paramilitaries "for acts of harassment and intimidation" in rural areas or inside camps for Darfur's 1.4 million displaced.
Earlier Sunday the US charge d'affaires to Sudan, Joseph Stafford, told reporters: "We're worried about the deteriorating security situation in Darfur and the conflict between the government forces and the militia."
While the worst of Darfur's violence has long passed, instability has been complicated by inter-Arab fighting, kidnappings, carjackings and other crimes, many suspected to be the work of government-linked militia and paramilitary groups.