Four protesters were shot dead and 14 wounded on Saturday during clashes between ethnic groups in the northern Iraqi oil city of Kirkuk that broke out after days of tensions.
The dispute centres on a building in Kirkuk that was once the headquarters for the Kurdistan Democratic Party (KDP) but which the Iraqi army has used a base since 2017.
The central government plans to return to the building to the KDP in a show of goodwill but Arab and Turkmen opponents set up a camp outside the building last week in protest.
The violence was sparked when a group of Kurdish protesters approached the camp on Saturday, police said.
Police and hospital sources had said earlier that one Kurdish protester was killed. The death toll rose after two more Kurdish protesters died in hospital from bullets wounds, they said.
Security officials and police in the city say they were investigating the circumstances of the deaths, including who opened fire. People from both protest groups were wounded as stones were thrown and metal bars used to attack, Kirkuk police said.
Prime Minister Mohammed al-Sudani ordered a curfew in the city to prevent an escalation of the violence, calling on "political parties, social organisations, and community leaders to play their part in preventing strife and preserving security, stability, and order".
Since Sudani took power last year, he has worked to improve relations between his government and the KDP. But Arab residents and minority groups who say they suffered under Kurdish rule have protested the KDP's return.