A roadside bomb exploded in the central Iraqi town of Khaldiya Tuesday, killing three American soldiers and at least one Iraqi civilian and injuring several other people. In Baghdad, U.S. soldiers discovered a car rigged with explosives near one of the entrances to the U.S. coalition headquarters.

The roadside bomb in Khaldiya detonated next to passing U.S. military vehicles. The incident took place early Tuesday afternoon local time.

Khaldiya is located in the volatile region referred to as the Sunni Triangle. It was once the heartland of Saddam Hussein's power base and is now at the center of attacks against coalition forces and Iraqis who cooperate with them.

Brigadier General Mark Kimmitt told reporters in Baghdad that despite such attacks, the overall number of incidents continues to decline. "The number of attacks has consistently gone down since mid-November, that is not sadly stopping the number of casualties," he said.

Several hours after the Khaldiya attack, bomb demolition experts were sent in to defuse a car bomb in central Baghdad. The explosives were found near one of the gates of the heavily guarded coalition headquarters.

The gate is close to the offices of the Iraqi Governing Council and not far from a convention center where the U.S.-led coalition holds routine media briefings.

Also Tuesday, two local employees of the Cable News Network (CNN) were killed. A driver and a producer were shot dead when gunmen opened fire on their convoy as it was returning to Baghdad from a reporting trip south of the capital.

At a news conference in Baghdad, Coalition spokesman, Dan Senor, welcomed the decision by U.N. Secretary-General Koffi Annan to possibly send a team to Iraq to assess the viability of early direct elections.

"The important point is for us to do everything we can to give the General Secretary the confidence that he needs that we are minimizing risk and maximizing the security of the electoral team that he will possibly deploy here," he said. "And, we have made it clear to him that we will make every effort."

The United Nations pulled its international staff out of Iraq following last August's bombing of the U.N. headquarters in Baghdad. A small U.N. security team has come to Iraq to assess the situation and see if it's safe to send U.N. staff back.