Hundreds of Afghan National Army (ANA) soldiers have been sent to the western city of Herat to try to keep the peace between two rival factions.
Correspondents say the fledgling army faces a big test in Herat
Fighting broke out after the death on Sunday of Afghanistan's Minister for Civil Aviation, who was also the son of Herat's governor, Ismail Khan.
Reports say up to 100 people have been killed in the factional skirmishing.
Members of one ANA battalion have arrived in Herat and more troops are due to reach the city on Tuesday.
Forces loyal to the governor in the western city regained control of Herat following the clashes triggered by Mirwais Sadiq's killing.
A spokesman for Governor Khan blamed his son's death on forces loyal to local military commander Zahir Nayebzada.
Mr Nayebzada is quoted as saying his forces killed Mr Sadiq during a confrontation when the minister tried to relieve him of his command.
The government has sent a high-level delegation to talk to local leaders.
The BBC's Crispin Thorold, in Kabul, says that Afghanistan's fledgling national army faces one of its biggest tests in the city.
The decision to deploy members of the ANA was taken by the Afghan cabinet, which has urged the citizens of Herat to help the government restore law and order.
It is still unclear how Mr Sadiq died. One report said a rocket-propelled grenade hit his car in Herat.
A defence ministry official in Kabul told Reuters news agency Mr Khan's troops were now in control of Mr Nayebzada's division.
The fighting ended soon after the US embassy in the Afghan capital, Kabul, issued a statement urging all involved "to remain calm and to abide by the rule of law and avoid further bloodshed".
Our correspondent says Ismail Khan controls Herat with what some describe as an iron fist. He is loved and loathed in equal measure.
Our correspondent says there have been rumours of rivalry between Mr Khan and Mr Nayebzada in recent weeks over the appointment of government jobs.
Ismail Khan, a former anti-Soviet resistance commander, is one of the most powerful men in Afghanistan with a strong following among ethnic Tajiks and a private army.
Correspondents say President Karzai has virtually no influence in the province, where Mr Khan has dominated since the end of Taleban rule in late 2001.