Three protestors were killed and 14 were injured in skirmishes between ethnic groups in the northern Iraqi oil city of Kirkuk on Saturday, according to security forces and police.

The conflict is on a structure in Kirkuk that was originally the headquarters of the Kurdistan Democratic Party (KDP), but has been utilized as a base by the Iraqi army since 2017.

The central government intends to restore the building to the KDP as a gesture of goodwill, but Arab and Turkmen opponents set up a protest camp outside the building last week.

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 organizations, and community leaders to play their part in preventing strife and preserving security, stability, and order”.

Kirkuk, an oil-rich province in northern Iraq along the fault lines between the Kurdish autonomous region and areas controlled by Iraq’s Shi’ite-dominated central government, has been the focus of some of the country’s worst post-Islamic State violence.

Kurdish forces controlled the city after driving Islamic State out in 2014 but were ejected by the Iraqi army in 2017.

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.