Ethnic Azerbaijanis, who constitute a large portion of the population in northwestern Iranian cities like Ardabil, Tabriz and Urmia, poured onto the streets Thursday, in support of Baku amid clashes in the Armenian-occupied Nagorno-Karabakh region.

The protesting groups demanded Iranian authorities close the country’s border with Armenia and the Norduz border gate, through which military equipment have reportedly been transferred to Armenia.

Video footage circulating on social media showed Iranian police breaking up the protests, using tear gas and rubber bullets.

Earlier Wednesday, Iranian authorities arrested at least 11 pro-Azerbaijan protesters, according to the Iranian Human Rights Activists News Agency.

It said police forces used tear gas to disperse activists, who had gathered at a park in Ardabil in solidarity with Azerbaijan in the wake of Armenian attacks.

Three activists were also wounded, it added.

Azerbaijani Turks constitute at least one-third of Iran’s 81.8 million population, according to different estimates. It was approximately 30 million according to Unrepresented Nations and Peoples Organization's (UNPO) 2017 data. They constitute the majority in northwestern provinces of Ardabil, East Azerbaijan, West Azerbaijan – bordering Azerbaijan – and Zanjan, in addition to significant population in adjacent provinces and capital Tehran.

Armenia and Azerbaijan have been locked in a bitter stalemate over the Nagorno-Karabakh region since the collapse of the Soviet Union.

The fiercest clashes between Armenian and Azerbaijani forces in years, over the occupied region, ignited Sunday. As of Thursday at least 130 deaths have been confirmed as fighting spilled over into the fifth day.

Four U.N. Security Council and two U.N. General Assembly resolutions, as well as many international organizations, demand the withdrawal of the occupying Armenian forces from Nagorno-Karabakh.

The OSCE Minsk Group – co-chaired by France, Russia and the U.S. – was formed in 1992 to find a peaceful solution to the conflict, but to no avail.

Nagorno-Karabakh is recognized as Azerbaijani territory by the U.N. and virtually every government in the world except Armenia.