The cause of the explosion on a busy street in the European side of Istanbul was not immediately known.
A police official said three people were injured 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.
Militant leftists and radical Islamists are also active in the country.
After the bombing in Ankara, Gen. Yasar Buyukanit, the military chief, warned that attacks could occur in other Turkish cities.
When General Wesley Clark spoke about the famous list of seven Middle Eastern countries to be demolished in five consecutive years, he has done nothing but remark, for the last time, if there was any need, Washington's willingness to redesign the Middle East within a more general framework of global domination.
In the region and in the worldб America and China seem to have become the major rivals. The Asia-Pacific region seems to have become the main area of this rivalry