BAGHDAD — A U.S. Army helicopter went down today south of Baghdad, and all nine aboard survived, although four were wounded, the military said.

Five U.S. troops were killed in separate attacks in Baghdad, and four British soldiers and a Kuwaiti interpreter were killed in an ambush in southern Iraq, officials said.

The military issued only a brief statement saying the helicopter went down and that the incident was under investigation.

An Iraqi army official said earlier that a Black Hawk helicopter had gone down after it came under fire at about 7:30 a.m. near the Sunni insurgent stronghold of Latifiyah, 20 miles south of Baghdad.

It was the ninth U.S. helicopter to go down in Iraq this year, raising concern among the military that insurgents are using more sophisticated weapons or have figured out how to use the old arms in new and effective ways.

The Iraqi official, who spoke on condition of anonymity because of security concerns, said the helicopter had gone down in a rural area and U.S. forces had cordoned off the site. He said the militants apparently were using an anti-aircraft heavy machine gun.

Latifiyah is part of the area dubbed the "Triangle of Death" because of frequent insurgent attacks.