The unrest flared just southeast of the Afghan capital Kabul when members of the Kuchi nomadic tribe clashed with guards working for a housing project linked to the family of lawmaker Qais Hasan.
Police said three people were killed and three others were wounded. But an AFP photographer was shown four bodies being carried by demonstrators in downtown Kabul.
The dispute is believed to be over a planned land development by the family of the politician opposed by the Kuchis, frequently seen on Afghan roads moving between areas with their herds of goats and other animals.
The interior ministry said an armed clash “over land” broke out between the Kuchis and the guards around 8:00 am (0330 GMT).
“Three people, all of them Kuchis, have been killed and three others have been injured,” added Kabul police spokesman Hashmat Stanikzai.
“Police have launched an investigation into the incident. Nobody has been detained yet.”
The Kuchis then brought their protest into the centre of Kabul, near President Hamid Karzai’s high-security palace and other key government offices, the AFP photographer at the scene said.
He added that some protesters were carrying sticks and burning tyres and that security forces had sealed off the area and were firing water cannon to try to control the crowd.
After hours of demonstrations, the angry mob agreed to leave the area, officials said. Hasan, the lawmaker, was not immediately contactable by AFP.
Pashtun nomads, estimated to number over two million in Afghanistan, roam the country in search of pastures for their camels, sheep and donkeys.