Insurgents fired mortars at an Iraqi National Guard headquarters north of Baghdad. The Defense Ministry says four people were killed and dozens of others were injured. Meanwhile, the head of a British charity in Iraq became the latest kidnapping victim, and U.S. forces continued to attack suspected insurgent positions in Fallujah.

Militants fired multiple mortars at the Iraqi National Guard building in the town of Adhamiya, about 30 kilometers north of Baghdad, in the latest attack on forces dedicated to restoring security in the country.

Iraq's Interior Ministry said some of the about 80 people who were wounded are in critical condition.

Insurgents have repeatedly attacked National Guard and Iraqi police forces throughout the country in an apparent effort to prevent the establishment of effective security forces. But the attack with mortars was on a larger scale than most of the previous incidents.

In the meantime, the chief of operations for CARE International U.K. has been kidnapped in Baghdad. Margaret Hassan, a dual Iraqi-British national, has been living in Iraq for 30 years, and doing charity work.

The Al-Jazeera television station has broadcast video of Ms. Hassan in captivity. Her identification papers were also shown, but it is not yet known who kidnapped her or what their demands are.

U.S. forces continued their campaign of bombing in the rebellious city of Fallujah, west of Baghdad. Bombing runs targeted alleged safe houses and weapons storage facilities that military officials believe are used by wanted militant Abu Musab al-Zarqawi and his followers in the southern part of the city.

A U.S. military statement says Mr. al-Zarqawi was planning to use foreign suicide bombers in vehicles rigged with explosives to launch attacks in Iraq. U.S. fighter jets have been attacking suspected positions of the al-Zarqawi group in Fallujah for several weeks.

On Sunday, someone claiming to represent the al-Zarqawi group issued a statement on the Internet declaring its allegiance to Osama bin Laden, the head of the al-Qaida terrorist network.