Masked gunmen stopped two minivans carrying students north of Baghdad Sunday, ordered the passengers off, separated Shiites from Sunni Arabs, and killed the 21 Shiites "in the name of Islam," a witness said.
In predominantly Shiite southern Basra, police hunting for militants stormed a Sunni Arab mosque early Sunday, just hours after a car bombing. The ensuing fire fight killed nine.
The two attacks dealt a blow to Iraqi Prime Minister Nouri al-Maliki's pledge to curb sectarian violence. He again failed to reach consensus Sunday among Iraq's ethnic and sectarian parties on candidates for interior and defense minister — posts he must fill to implement his ambitious plan to take control of Iraq's security from U.S.-led forces within 18 months.
Violence linked to Shiite and Sunni Arab animosity has grown increasingly worse since Feb. 22, when bombs ravaged the golden dome of a revered Shiite mosque in predominantly Sunni Arab Samarra.
Sectarian tensions have run particularly high in Baghdad, Basra and Diyala province, a mixed Sunni Arab-Shiite region. And Sunday's attacks came just days after terrorist mastermind Abu Musab al-Zarqawi renewed his call for Sunni Arabs to take up arms against Shiites, whom he often vilifies as infidels.
In other developments:The top officer in the U.S. military pledged a thorough investigation into the alleged massacre of Iraqi citizens in Haditha by Marines, saying it is important to avoid a rush to judgment. Gen. Peter Pace, chairman of the Joint Chiefs of Staff, acknowledged that the allegations involving the deaths of about two dozen Iraqis have raised concerns among Iraqi officials and in the United States. Secretary of State Condoleezza Rice told Bob Schieffer on Face The Nation promised that the Pentagon will "get to the bottom" of the Haditha investigations.Injured CBS News correspondent Kimberly Dozier will remain at a military hospital in Germany for a few more days before returning to the United States. Though Dozier had been looking forward to going home Sunday, wounded soldiers with more urgent needs had to be flown out before her. She may be flown back as early as Tuesday. Iraqi security forces were searching Baghdad for four Russian diplomats kidnapped Saturday. Another Russian diplomat was killed in the attack that took place near the embassy in west Baghdad's Mansour district. U.S. Ambassador Zalmay Khalilzad condemned the attack and promised to help seek the release of the hostages. Rep. Christopher Shays says he regrets failing to be more aggressive in overseeing the Pentagon's Iraq war plan, particularly by demanding more accountability on cost estimates. "I fault myself," Shays, R-Conn., said in an interview with the Connecticut Post published Sunday. "I was hearing voices in my own head that this was going to cost more and I accepted the Pentagon numbers that were too low. I should have had hearings early on." The U.S. military said an American soldier was killed Saturday in the volatile Anbar province.
© 2006 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.