Security camera footage showed the women firing at a police bus outside a riot police station in Istanbul's Bayrampasa neighborhood and also hurling a hand grenade, before apparently taking aim at the police station. The hand grenade did not explode.
They escaped the scene in a vehicle and hid inside a building a short distance from the police station. Police quickly surrounded the building and launched an operation after the pair ignored calls for them to surrender.
Sahin said police were trying to identify the assailants and possible accomplices.
There was no immediate responsibility claim for the attack on the riot police station. Both Kurdish rebels and militants of a far-left organization have attacked police in the city in the past.
The attack comes amid a surge in violence in Turkey since the summer.
A fragile peace process with the Kurdistan Workers' Party, or PKK, collapsed in July, reviving a three-decade conflict that has killed tens of thousands of people since 1984.
A Kurdish militant group that is an off-shoot of the PKK claimed responsibility for that attack. But the government maintains that it was the work of a Syrian Kurdish militia group, in coordination with the PKK.
Some 145 people have died since July in three separate suicide bomb attacks that authorities have blamed on the Islamic State group, including 12 German tourists who were killed in Istanbul's historic Sultanahmet district on January 12.
