Report: 3 Teens Held in Turkey Bombing That Killed 17

Turkish officials suggested Monday that Kurdish militants were the main suspects in bomb blasts that killed 17 people in a crowded square, with Turkey's prime minister saying it could be a reprisal for air raids on guerrilla positions in northern Iraq.

The rebel Kurdistan Worker's Party, or PKK, immediately denied involvement and attributed Sunday night's attack to "dark forces," an apparent reference to hardline Turkish nationalists who allegedly seek to foment chaos in order to strengthen the political influence of the military.

As of Monday morning, nobody had yet claimed responsibility. Turkey is home to a variety of militant groups besides the PKK, including Islamic extremists and alleged coup plotters with ties to the secular establishment.

"I feel deep grief from this cowardly attack that targeted innocent citizens and I curse them with hatred," said Gen. Yasar Buyukanit, the military chief. "The fact that the attack was carried out in a vibrant street at a time when there were crowds once again shows the savagery, the desperation and the bloody face of terrorism."

The twin blasts happened on the eve of a Turkish court's deliberations on whether to ban the Islamic-oriented ruling party for allegedly trying to undermine secularism, and the timing raised questions about whether there was a link.

The attack and the legal challenge to the government highlight a growing mood of uncertainty in Turkey, where an Islamic-oriented government that won a strong mandate in elections last year is locked in a power struggle with secular circles in the military and judiciary.

Prime Minister Recep Tayyip Erdogan flew to Istanbul after canceling a Cabinet meeting in the capital, Ankara. At the bombing scene, he suggested that Kurdish militants acted in revenge for air raids on PKK positions in northern Iraq, as well as a cross-border ground offensive by the Turkish military in February.

"Unfortunately, the costs of this are heavy," Erdogan said. "The incident last night is one of them."

The prime minister urged Turks not to back political parties that "support terrorism," an indirect criticism of the Democratic Society Party, a pro-Kurdish group believed to be heavily influenced by the PKK.

The United States and the European Union say the PKK, which seeks autonomy for Kurds, is a terrorist organization.

Istanbul Gov. Muammer Guler said the rebel group seemed to be connected to the deadliest attack against civilians in Turkey in five years.

"There appears to be a link with the separatist organization," Guler said. "We are working on that."

A pro-Kurdish news agency, Firat, reported that a Kurdish rebel leader denied the PKK was responsible.

"The Kurdish freedom movement has nothing to do with this event, this cannot be linked to the PKK," Firat quoted the leader, Zubeyir Aydar, as saying. "We think this attack was carried out by dark forces. We extend our condolences to the families of the victims and to the Turkish people."

The bombs went off in the residential neighborhood of Gungoren in a busy square closed to traffic where people congregate at night. Authorities said the vast majority of the 17 deaths and 150 injuries occurred when a curious crowd gathered after an initial, small blast.

Erdogan said 100 of the injured were later released from hospitals after treatment.

"First, they exploded a percussion bomb to grab attention. Then, 10 minutes later, in another trash can, they exploded a fragmentation bomb," said Deputy Prime Minister Hayati Yazici.

The Cihan news agency said the second bomb consisted of a plastic explosive of the same kind that was used in a suicide attack in a shopping thoroughfare in Ankara in May 2007 that killed 7 people. That attack was blamed on the PKK.

Five of the dead were children, said Guler, the governor. Anatolia news agency said one victim was a 12-year-old girl who rushed with her parents to the balcony of their fourth floor apartment to see what was going on after the first explosion.

The attack was the country's worst since November 20, 2003, when al-Qaida linked suicide bombings struck the British consulate and a British bank, killing at least 30 people. Five days earlier, suicide truck bombs attacked two Istanbul synagogues, killing 27.

On July 9, gunmen opened fire on police guarding the U.S. consulate in Istanbul, killing three officers. Three attackers also died in a shootout with police. Authorities were investigating whether the gunmen were inspired by Al Qaeda.