ISTANBUL, Turkey --
Armed men opened fire Wednesday on Turkish police guarding the front entrance to the U.S. consulate in Istanbul, killing three policemen in what Turkish and U.S. officials called a terrorist attack. Three assailants were also reported killed.
The U.S. ambassador to Turkey, Ross Wilson, and Turkey's foreign ministry said security around all U.S. diplomatic missions in Turkey was immediately increased after the attack, which began about 11 a.m. on the high-walled compound in the Istinye district.
All U.S. consulate staff were safe and accounted for, Wilson said.
There was no immediate claim of responsibility for the attack. Interior Minister Besir Atalay said police would not reveal the identities of the slain attackers or their possible affiliations for the sake of the investigation.
Footage from a security camera at the site showed four armed and bearded men emerging from a gray car to kill a traffic policeman, then running toward the guardpost 50 meters (yards) away as other policemen fired back, the Dogan news agency reported.
The shootout caused panic and scattered people waiting in visa queue, Dogan said. U.S. security personnel then ducked inside the compound since they are not authorized to engage in armed action on Turkish soil.
Three of the attackers were killed in the shootout, U.S. and Turkish officials said. The video showed a fourth attacker jumping into the speeding gray vehicle and fleeing, Dogan reported.
Police are pursuing an unknown number of attackers who escaped.
Istanbul prosecutor Aykut Cengiz Engin said the attackers were armed with pistols and shotguns. Forensic teams later examined a shotgun on the ground.
Television footage showed four people lying on the ground at the foot of the consulate's wall. The bodies were later removed.
"There is no doubt that this is a terrorist attack," Istanbul Gov. Muammer Guler told reporters at the scene, calling the three slain policemen martyrs. Two other people, a policeman and a truck driver, were injured, he said.
Yavuz Erkut Yuksel, a bystander, told CNN-Turk television the gunmen surprised the guard.
"One of them approached a policeman while hiding his gun and shot him in the head," Yuksel said.
Guler said two of the attackers were Turkish, denying speculation that they had Syrian passports.
The U.S. ambassador refused to speculate on the identity of the attackers but stressed that the United States and Turkey would keep working together against terrorism.
"It is, of course, inappropriate now to speculate on who may have done this or why. It is an obvious act of terrorism," Wilson said. "Our countries will stand together and confront this, as we have in the past."
He also praised Turkish police for responding quickly to the attack.
The secure U.S. consulate building was built after homegrown Islamic militants linked to al-Qaida carried out suicide bombings in 2003 that targeted two synagogues, the British Consulate and a British bank in Istanbul. Those attacks killed 58 people.
Some of those suicide attackers had trained in al-Qaida camps in Afghanistan. CNN-Turk television reported that some of Wednesday's attackers had traveled to Afghanistan previously, but police would not confirm the report.
Dogan identified one of the attackers as 26-year-old Erkan Kirgiz from the southeastern city of Bitlis. Police would not confirm the report.
The consulate occupies an imposing structure on a hill in Istinye, a densely residential neighborhood along the Bosporus Strait on the European side of Istanbul.