Three policemen and three gunmen killed in terrorist assault on U.S. consulate in Istanbul

Three gunmen launched a frontal assault on the United States consulate during rush hour, the city's governor said.

All three were killed at the scene together with one of the police officers during what witnesses said was a 15-minute gunfight, according to Governor Muammer Guler.

Bloody battle: An unidentified man lies on the ground lifeless after an attack outside of the U.S. Consulate in Istanbul

Two more died of their wounds at a nearby hospital.

Television images showed paramedics carrying out heart massage on one of those lying on the ground. The shirts of one of the men was ripped open. Blood was flowing from the head of another person.

Four bodies lay on the ground in front of the high-walled compound situated outside Istanbul city centre, overlooking the Bosphorus waterway.

'They (assailants) were four people. Three of them got out of the car and fired at the police,' said eye-witness Enis Tilmaz.

Mt Yilmaz who was at the consulate for a visa application, added: 'I saw them dead afterwards lying on the ground and many more dead among the police.'

The fourth man drove off.

It was reported that one of the dead police officers was working at the consulate while the other two were traffic officers.

Ulus Durgut, 24, who was going to the heavily-guarded compound on the European side of Istanbul, said the gunbattle lasted 15 minutes.

'The terrorists were bearded men and had long hair,' Durgut added.

Police have launched an operation to capture the armed assailants who escaped.

Turkey has seen armed attacks from a variety of groups over the years, including Maoists, Trotskyists, Kurdish separatists and Islamist militants.

The most serious incidents were in November, 2003, when 62 people were killed in attacks by Islamist militants on two synagogues, a bank and the British consulate.

Since then, security has been stepped up at most major consulates and embassies in Turkey.

Four people were killed and 15 wounded in an explosion in Istanbul, before U.S. President George W. Bush visited the city in June 2004.