An explosion in a street in Istanbul wounded at least 14 people Sunday, police said. The cause of the explosion on a busy street in the European side of the city was not immediately known. A McDonald's restaurant is among businesses near the site of the blast. A police official said 14 people were wounded in the blast, which comes amid heightened tension in Turkey over attacks by separatist Kurdish rebels. The official was speaking on condition of anonymity because of rules that bar civil servants from speaking to journalists without prior authorization. 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.