ISTANBUL, March 3 -- Turkish police shot dead two female militants on Thursday after they fired shots and threw a grenade at a Turkish police bus in Istanbul, local media and the city governor said.

A radical leftist group claimed responsibility for the attack, in which two police officers were lightly wounded, Governor Vasip Sahin said in televised comments.

One woman threw a grenade and the other opened fire with what appeared to be a machine gun as the riot police bus headed for the entrance of a police station in the Bayrampasa district of Turkey's biggest city, footage from Dogan News Agency showed.

Police fired back, injuring one of the women, before tracking them to a nearby building, CNN Turk said.

Special forces units and police surrounded the building, television footage showed, leading to an hour-long stand-off in which there was sporadic gunfire and the women were shot dead.

A claim of responsibility came from a website close to the Revolutionary People's Liberation Party-Front (DHKP-C), a group that has repeatedly targeted police stations, largely in Istanbul suburbs.

Attacks on Turkey's security forces have also increased as violence has resurged in the predominantly Kurdish southeast, where a ceasefire between Kurdistan Workers' Party (PKK) militants and the state collapsed last July.

The PKK, considered a terrorist group by Turkey, the United States and the European Union, launched a separatist armed rebellion against Turkey in 1984. More than 40,000 people, mostly Kurds, have since been killed.

Turkey has also become a target for Islamic State militants, who are blamed for three suicide bombings - one last year in the town of Suruc near the Syrian border and another in the capital, Ankara, and one in Istanbul in January. Those attacks killed more than 140 people.

A suicide car bombing targeted military buses in Ankara and killed 29 people last month. The government said that attack was carried out by a member of the YPG, the Syrian Kurdish militia, with help from PKK militants.