BAGHDAD, Iraq – Insurgents brought down a Russian-made helicopter carrying 11 civilians with missile fire north of the capital yesterday and said they captured and shot to death the lone crew member who survived. The dead from the crash included six American bodyguards for American diplomats.

The chartered flight was believed to be the first civilian aircraft shot down in Iraq since the American-led invasion two years ago.

An Internet statement by a group identifying itself as the Islamic Army in Iraq was accompanied by a video showing the shooting of a man who was found in tall grass and forced to stand up and walk. The video showed burning wreckage just before the shooting.

“One of the crew members was captured and killed,” the statement said.

The man who was shot to death in a grassy field spoke English with an accent and was wearing a blue flight suit, indicating he was one of the three Bulgarian crew members. Two Fijian helicopter security guards were also onboard the flight.

The video also showed two charred bodies near the burning wreckage, about 12 miles north of Baghdad.

The authenticity of the video, posted on a Web forum often used by militant groups, could not be confirmed. An American Embassy official in Baghdad said he had no knowledge that anyone on board survived the crash and was killed later.

The Mi-8 helicopter was shot out of the air as growing numbers of contractors, diplomats, and other civilian officials are turning to aircraft to avoid insurgent attacks on Iraq’s roads.

The downing is part of a surge of attacks that have caused heavy casualties in recent weeks, ending a relative calm since January elections. In the latest violence, two American Marines and at least five other people, including two foreign civilians, were killed in attacks Wednesday and yesterday.

The six Americans on board the downed helicopter were employed by Blackwater Security Consulting – a subsidiary of North Carolina-based security contractor Blackwater USA, which had four employees slain and mutilated by insurgents at Fallujah a year ago.

The Americans were assisting the Bureau of Diplomatic Security in protecting American diplomats in Iraq.

“They played a critical role in our effort to bring a better way of life to the people of a country who have not experienced freedom and opportunity for many years,” State Department spokesman Adam Ereli said.

The Islamic Army statement said it killed the survivor “in revenge for the Muslims who have been killed in cold blood in the mosques of tireless Fallujah before the eyes of the world and on television screens, without anyone condemning them.” It was apparently referring to the shooting by an American soldier of a wounded Iraqi in a Fallujah mosque on November 13 during an American offensive in the city.

In the video, militants come across the injured man in the flight suit. “Stand up! Stand up!” an insurgent orders the man, who reaches out and says, “Give me a hand.”

Then, apparently referring to a fractured leg, he says, “It’s broken.”

The militants – unseen except in brief glances – tell him to stand up. “Weapons? Weapons?” the gunmen ask him in Arabic as he stands uneasily.

They tell him, “Go!” and he starts to hobble away with his back to the camera. Then there are voices and he turns to the side, holding up a hand. Then the shooting begins, bullets hitting his body as he falls backward into the grass. The insurgents can be heard shouting “Allahu akbar,” or “God is great,” as he goes down. More bursts of gunfire then hit the body.

Mr. Ereli, who spoke before the video was posted, said he could not confirm the cause of the crash. However, the Bulgarian Defense Ministry said the helicopter was struck by missile fire.

The aircraft was owned by Heli Air of Bulgaria and chartered by Toronto based SkyLink Aviation. It was flying to Saddam Hussein’s hometown of Tikrit from Baghdad’s heavily guarded Green Zone, home to Iraq’s parliament and many diplomats.

Mr. Ereli said the American government routinely hires contractors to provide security for diplomats, facilities, or the activities of people connected with the government.

“There is a need for security that goes beyond what employees of the U.S. government can provide and we go to private companies to offer that,” Mr. Ereli said. “That’s a common practice. It’s not unique to Iraq. We do it around the world.”

Yesterday’s helicopter crash was thought to be the first shoot-down of a civilian aircraft in Iraq since the invasion in March 2003.