BAGHDAD, Iraq -- Insurgents struck Tuesday at the center of the U.S.-led occupation, firing mortars after sundown at the heavily guarded district that includes major American facilities. Three people were wounded, the Pentagon said.

Spain, a close U.S. ally, withdrew many of its diplomats because of escalating violence.

Huge explosions thundered throughout central Baghdad about 7:45 p.m. as the insurgents targeted the 2-square-mile "Green Zone," which includes coalition headquarters, the military press center and other key facilities.

Iraqi police said two mortars fell in the zone, but U.S. officials said the headquarters itself, located in one of Saddam Hussein's former palaces, was not damaged.

However, the huge detonation sent coalition staffers running into the hallways. It was the second mortar attack against the Green Zone in as many days.

At the Pentagon, spokesman Lt. Col. Jim Cassella said three people were wounded in the attacks but it was unclear if they were military or civilians.

The deteriorating security situation has prompted the United Nations, the international Red Cross and other international organizations to reduce their foreign staffs.

On Tuesday, Foreign Minister Ana Palacio said Spain will withdraw 25 of the 29-member Spanish diplomatic staff from Baghdad. Most will be relocated to Amman, Jordan. Spain has about 1,300 soldiers in Iraq and was one of the strongest supporters of the U.S.-led invasion.

"We have taken staff out of Baghdad temporarily given that it is a very complicated moment," Palacio said in Berlin. Spaniards working for the U.S.-led Coalition Provisional Authority will stay, the Spanish Defense Ministry said without giving their number.

Elsewhere, insurgents Tuesday ambushed a U.S. patrol with rocket-propelled grenades in Khaldi-yah, a town west of Baghdad in the volatile "Sunni Triangle," witnesses said. There was no report of casualties and no confirmation from the U.S. command.

The Arabic language satellite television station Al-Jazeera reported an ambush Tuesday near Samara north of the capital and broadcast pictures of cheering Iraqis displaying American ammunition as a truck burned in the background.

U.S. troops, meanwhile, raided the village of Karasia near Tikrit late Monday, arresting two suspects and seizing Kalashnikov rifles, 14 mortar rounds, a mortar tube, and rocket-propelled grenades and launchers, the military said.

In Mosul, gunmen killed a provincial judge Tuesday near his home. Ismail Youssef, a Christian, was a deputy to the head of the appeal courts in Nineveh province.

On Monday, the head of an Iraqi court who was investigating members of Saddam Hussein's Baath Party, Muhan Jabr al-Shuweily, was abducted and murdered in the southern city Najaf.

A colleague who was spared said he believed the killers were supporters of Saddam.

The Spanish withdrawal followed the slaying of a Spanish navy captain in the truck bombing of the U.N. headquarters in Baghdad on Aug. 19, and the Oct. 9 killing of a Spanish sergeant working for military intelligence. Security at the Spanish Embassy had been stepped up in recent weeks.

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Associated Press writers Mariam Fam in Mosul, Katarina Kratovac in Tikrit and Bassem Mroue in Baghdad contributed to this report.