A suicide bomb attack at a busy shopping area in the Turkish city of Istanbul has killed at least four people, officials say.
Up to 20 people were injured, three seriously.
The area - Istiklal Street - is reportedly crowded at weekends.
Last Sunday, an attack in the capital, Ankara, killed 37 people. A Kurdish militant group claimed that attack, saying it was in revenge for Turkish military operations against Kurds.
Last month, a bomb attack on a military convoy in Ankara killed 28 people and wounded dozens more.
In October 2015, more than 100 people were killed in a double-suicide bombing at a Kurdish peace rally in Ankara.
President Recep Tayyip Erdogan said terror groups were targeting civilians because they were losing their struggle against Turkish security forces.
He said such attacks "increase our determination to fight terrorism".
Turkey has previously blamed Syrian Kurds and carried air strikes in retaliation.