ISTANBUL--A car bomb ripped through a police bus in central Istanbul during the morning rush hour on Tuesday, killing 11 people and wounding 36 near the main tourist district, a major university and the mayor's office.
The car was detonated as police buses passed, Istanbul Governor Vasip Sahin told reporters, in the fourth major bombing in Turkey's biggest city this year. There was no immediate claim of responsibility but Kurdish militants have staged similar attacks on the security forces before, including one last month in Istanbul.
Security concerns were already hitting tourism and investor confidence. Wars in neighbouring Syria and Iraq have fostered a home-grown Islamic State network blamed for a series of suicide bombings, while militants from the largely Kurdish southeast have increasingly struck in cities further afield.
President Tayyip Erdogan vowed the NATO member's fight against terrorism would go on, describing the attack on officers whose jobs were to protect others as "unforgivable". "We will continue our fight against these terrorists until the end, tirelessly and fearlessly," he told reporters after visiting some of the injured in a hospital near the blast site.
Sahin said the dead included seven police officers and four civilians and that the attack had targeted vehicles carrying members of a riot police unit. Three of the 36 wounded were in critical condition, he said.
The White House condemned the attack, and National Security Council spokesman Mark Stroh said in a statement, "This horrific act is only the most recent of many terrorist attacks against Turkey. The United States stands together with Turkey, a NATO ally and valued partner, as we confront many challenges in the region."
The bomb was planted in a rental car and was detonated by remote control, the Dogan news agency said, without citing its sources. It said four people had been detained.
The blast on the second day of the Muslim holy month of Ramadan hit the Vezneciler district, between the headquarters of the local municipality and the campus of Istanbul University, not far from the city's historic heart. It shattered windows in shops and a mosque and scattered debris over nearby streets.
"There was a loud bang, we thought it was lightning but right at that second the windows of the shop came down. It was extremely scary," said Cevher, a shopkeeper who declined to give his surname. The blast was strong enough to topple all the goods from the shelves of his store.
The police bus that appeared to have borne the brunt of the explosion was tipped onto its roof on the side of the road. A second police bus was also damaged. The charred wreckage of several other vehicles lined the street.
