Iraqi authorities say more than 30 gunmen have attacked the Health Ministry building in Baghdad, sparking fierce clashes with security forces

Officials say the attackers fired mortar rounds at the building and that ministry workers appeared to be trapped inside. There are no immediate reports of casualties.

Meanwhile, the U.S. military says Iraqi forces, along with Coalition advisers, conducted a raid in Baghdad's Sadr City district to capture a kidnapping and murder cell leader. A military statement says the cell leader is believed to have knowledge of the whereabouts of a U.S. soldier kidnapped last month.

Iraqi witnesses say four people were killed by U.S. forces in Sadr City. The U.S. military has not commented on the report.

Separately, Vice President Dick Cheney's office is denying reports that he is in Baghdad to spend Thanksgiving with U.S. troops.

The office issued the denial shortly after Iraqi state television reported Cheney was in Baghdad for a previously unannounced visit.

In other developments, the U.S. military says three Marines died of wounds sustained due to enemy action in western Al Anbar province Wednesday.

A U.N. report says more than 3700 Iraqi civilians were killed in October -- the highest monthly toll since U.S. forces invaded the country in 2003.

Some information for this report was provided by AP, AFP and Reuters.