Turkey's state-run news agency says a woman opened automatic weapon fire at a police vehicle in Istanbul's main square, Taksim, before escaping on foot.
No one was hurt in Friday's incident.
The Anadolu Agency says the assailant left her weapon and a bag near the square. There was no immediate responsibility claim.
It is the third in a string of recent attacks against police in Istanbul. On January 1, police subdued a man after he threw grenades and fired a weapon at officers near the prime minister's offices. On January. 6, a suicide bomber killed a police officer and wounded another in a tourist district.