A female suicide bomber blew herself up in a popular tourist district of Istanbul, killing one police officer and injuring another, officials say.
She targeted a police station in the tourist hub of Sultanahmet, near the Blue Mosque and Hagia Sophia museum.
Police sealed off an area in the historic district of the Turkish city.
The attack briefly shut down public transport around Sultanahmet square, a popular tourist destination visited by thousands of people every day.
The Foreign and Commonwealth Office said in an updated travel advisory: “If you’re in this area you should follow the advice of the local authorities.”
The woman spoke English with “a thick accent”, but her nationality and identity remained unknown, Istanbul governor Vasip Sahin told Turkish TV.
He said the woman, dressed in a niqab, entered the police station and told officers she had lost her wallet before detonating the bomb.
No group has yet said it was behind the attack, the second on police in a week.
Police arrested a man who threw grenades and fired a weapon at officers near the prime minister’s office last Thursday, but no one was injured in that attack.