ISTANBUL, Turkey – Authorities detained four suspects Thursday in connection with the attack on the U.S. consulate in Istanbul that ignited a firefight that left three policemen and three assailants dead.
Police and Turkey's intelligence agency were also investigating whether one of the slain gunmen had any relationship with Al Qaeda when he visited Afghanistan. Police suspect the attackers had ties to Al Qaeda but so far say they have no actual proof.
• Click to view photos of the attack.
Interior Minister Besir Atalay said Thursday that four people were in custody. One of the attackers escaped in a getaway car, but it was not immediately clear if he was among the four detained.
Erkan Kargin, one of the three attackers killed by police outside the consulate, had previously traveled to Afghanistan, according to a government official, who spoke on condition of anonymity because he was not authorized to speak to the media.
Dozens of militants from Turkey have had military training in Al Qaeda camps in Afghanistan and some also fought and died in Al Qaeda ranks in Iraq, Turkish officials say.
Wednesday's attack came less than five years after local Islamic militants, loosely connected to Al Qaeda, killed 58 people in four suicide bombings against two synagogues, the British consulate and the local headquarters of HSBC bank.
"There is nothing more sensational than attacking the U.S. consulate for an Islamic militant," said Emin Demirel, a Turkish terrorism expert and author of a book titled "Al Qaeda Elements in Turkey." "However, this attack certainly lacks the sophisticated hallmarks of Al Qaeda."
Three gunmen were killed by police at the scene and a fourth attacker used a runaway car to escape, not the usual Al Qaeda tactics of suicide bombings and mass civilian casualties.
The attack prompted Turkey to increase security at all U.S. diplomatic missions in the country.
If Kargin's suspected relationship with Al Qaeda is confirmed, police are likely to label the attackers as militants linked to Al Qaeda in Turkey, said Demirel, the Turkish terrorism expert.
Homegrown Islamic militants have been posing an increasing threat to Turkey. As both a secular state and a U.S. ally, it is a high-profile target for Islamists who subscribe to Al Qaeda's world view.
"Al Qaeda has chosen Turkey as a main target and it would not be wrong to assume that the group would have instructed cells in Turkey to act," said Ihsan Bal, head of terrorism studies at Ankara-based International Strategic Research Organization.
Still, he added this does not mean Al Qaeda leaders are issuing direct orders to all their Turkish adherents.
"In Turkey, not all Al Qaeda cells have direct organic links with the group in Afghanistan. There are many groups that have taken on Al Qaeda's ideology and act on their own initiative," said Bal.
The Hurriyet newspaper suggested Wednesday's attack could have been done in revenge for the death of an Al Qaeda militant, Abdul Fettah, reportedly killed in Afghanistan by a U.S. bombing.
Fettah and two of the three slain consulate assailants, Kargin and Raif Topcil, are all from the same southeastern province of Bitlis, a Kurdish-dominated region where radical Islam has long had a stronghold.
But police have been careful not to single out Kurds — many of whom support an autonomy-seeking Marxist Kurdish rebel organization, the PKK — alone for their role in radical Islamic organizations.