ANKARA, Turkey, (AP) -A small bomb exploded outside a clothing shop in Istanbul on Sunday, injuring 14 people and shattering nearby windows, police and news reports said, amid heightened tensions over attacks by separatist Kurdish rebels.

The bomb appeared to be a type of explosive that usually makes a loud noise but causes limited damage, police said. The official was speaking on condition of anonymity because of rules that bar civil servants from speaking to journalists without prior authorization.

The state-run Anatolia news agency said 14 people were injured in the bomb, left beneath a bench. NTV television said none of the injuries was life-threatening.

Last month, a suicide bomb attack in Ankara killed eight people and injured dozens of others. Turkish officials blamed the rebel Kurdistan Workers’ Party, or PKK, for the attack. The group denied involvement.

Militant leftists and radical Islamists are also active in the country.

After the bombing in Ankara, Gen. Yasar Buyukanit, the military chief, warned of possible attacks in other Turkish cities.