BAGHDAD, Iraq - A mortar attack on an Iraqi National Guard headquarters north of Baghdad today killed four guardsmen and wounded 80 others, the U.S. military said. The director of CARE International in Iraq was kidnapped in the latest attack targeting humanitarian organizations.

The guardsmen were lined up in formation when six mortars hit the National Guard offices in an early morning attack in Mashahidah, 25 miles north of Baghdad, said international officials and National Guard officers under condition of anonymity.

The U.S. military cited the Iraqi Defense Minister as saying four guard members were killed and 80 others wounded. The military said multinational forces helicopters helped ferry out the wounded.

The Iraqi National Guard has been a frequent target of insurgents trying to undermine U.S.-led security efforts ahead of national elections.

In northern Iraq, saboteurs attacked and set on fire a key oil pipeline that connects the Beiji oil refinery with Turkey, police said today. The pipeline was hit with explosives late Monday, said a Beiji police officer. An official at the state-run Northern Oil Company confirmed the attack, but did not say whether it would affect exports.

Iraq's oil industry has been hit by repeated insurgent attacks, hampering attempts to rebuild a sector that provides desperately needed money for Iraq's reconstruction efforts.

The abduction of CARE International's director was the latest kidnapping targeting foreigners in the heart of the Iraqi capital.

Margaret Hassan, said to be a British-born Iraqi national, was abducted while she was being driven to work in a west Baghdad neighborhood, said a CARE employee speaking on condition of anonymity. The employee said CARE did not employ armed guards.

"As of now we are unaware of the motives for the abduction," CARE International, United Kingdom said in a statement released in London and read to The Associated Press in Baghdad. "As far as we know, Margaret is unharmed." The statement said she was abducted in Baghdad at 7:30 a.m. but gave no details.

Humanitarian organizations have not been spared from the violence sweeping Iraq. Last year, the Iraq headquarters of the International Committee of the Red Cross was damaged by a vehicle bomb, and many non-governmental organizations have withdraw foreign staff because of the bombings and kidnappings of foreigners.

Insurgents in Iraq have kidnapped more than 150 foreigners in their campaign to drive out coalition forces.