Turkish police have arrested two people after shots were fired at officers guarding Istanbul's Dolmabahce Palace, an Ottoman-era palace that is a major tourist attraction, Turkey's state-run news agency said.
One police officer was slightly injured, the Anadolu Agency said.
A percussion bomb also went off outside the palace, situated on the shores of the Bosphorus strait. It houses an office of the Turkish prime minister, but he was in the capital Ankara at the time of the attack.
Police apprehended two people in an area close to the palace and seized two hand-grenades, an automatic rifle, a hand gun and a large amount of ammunition, a statement from the Istanbul governor's office said. It did not identify the suspects or give a motive for the attack.
The incident comes amid an escalation of violence between Turkey's security forces and Kurdish fighters, and as Turkey has been conducting operations against groups including the Islamic State of Iraq and the Levant (ISIL) group.
Turkey has rounded up more than 1,000 people linked to ISIL, Kurdish groups and leftist armed groups.
On Wednesday, Turkish state media reported that at least eight soldiers were killed following a roadside bomb attack in Siirt province.
According to the Anadolu Agency, the bomb exploded on a highway in the mainly-Kurdish province as their military vehicle was passing by.