Four Arab men have been arrested in the Iraqi city of Najaf in connection with Friday's bombing at a Muslim shrine that killed more than 100 people and injured more than 140. Iraqi authorities say the men have close ties with Osama bin Laden's al-Qaida terrorist network.
Iraqi police said Saturday the four men, two Iraqis and two non-Iraqis, were arrested shortly after the explosion. The blast was described as similar to recent attacks at the United Nations headquarters and the Jordanian embassy in Baghdad that between them killed 42 people.
U.S. officials have said that foreign terrorists aiming to destabilize the country have been coming across Iraq's porous borders from Syria, Saudi Arabia and Iran.
Family members continued searching for loved ones in local hospitals where the dead and wounded have been taken.
The spiritual leader of one of Iraq's most powerful Shia groups was killed in the explosion. Ayatollah Mohammed Baqir al-Hakim died as he was leaving Friday prayers outside the mosque that is the burial place of the son-in-law of the prophet Mohammed and Iraq's holiest Shia shrine.
Ayatollah al-Hakim was seen as a moderate influence on Iraq's Shiite population and had called for cooperation with U.S. forces in the country.
American authorities condemned the deadly blast as an act of terrorism and blamed it on those who will stop at nothing to destabilize Iraq.
Thousands of people Saturday thronged the area in Najaf where Friday's bomb exploded. Carrying banners and chanting, the crowds denounced the bombing and vowed to avenge the attack that now threatens the delicate balance of religious and political power in the war-torn country.
Angry Shiites initially blamed the bomb on remnants of Saddam Hussein's regime, but they also showed growing anger toward U.S. forces for failing to provide security that could have prevented such an attack.
No U.S. forces were on duty nearby when the bomb went off Friday, because Shi'ite Muslim clergy in Najaf have opposed the deployment of any troops in the holy city.