Four U.S. missionaries were slain in a drive-by shooting in the northern city of Mosul on Tuesday. A fifth American was being treated at a U.S. military hospital.
Hours later, reports emerged that two German civilians and two Iraqis, including a driver and a policeman, were killed in an ambush south of Baghdad.
Two Iraqi police were also wounded in the attack near the town of Mussayab, 45 miles south of Baghdad, said Dr. Jamal Kadhim, head of the emergency department at Mussayab General Hospital.
An Iraqi woman whose sister works for the coalition was also killed, perhaps in a case of mistaken identity. Last week, two American civilians working for the Coalition Provisional Authority and their Iraqi interpreter were slain in an ambush.
Many civilian aid workers already fled Iraq after bomb attacks on United Nations and Red Cross facilities last year.
"Clearly there has been a shift in the insurgency and the way the extremists are conducting operations," Lt. Gen. Ricardo Sanchez said during a military ceremony in the northern city of Tikrit. "It is very clear they are going after these targets that might create some splits within the coalition."
In other developments:
Sanchez said the coalition could continue without Spain's contribution.
"It is something we will have to adjust to," the general said. "But it is clearly manageable. It is not a significant military problem for the coalition to be able to cover that area."
Zapatero's Socialist party was propelled to an upset victory in elections Sunday by anger over terrorist attacks in Madrid last week that killed 200 people.
Shockwaves from the Madrid bombing were felt by other U.S. allies in Iraq. South Korea's acting President Goh Kun tightened security on Tuesday. Australia urged Spain not to withdraw, saying doing so would be seen by some as a "victory" for terrorists. Poland said it has no extra troops to send to Iraq if Spain makes good on its threat.
The Virginia-based Southern Baptist International Mission Board identified the four dead as Larry T. Elliott, 60, and Jean Dover Elliott, 58, of Cary, North Carolina; Karen Denise Watson, 38, of Bakersfield, California; and David E. McDonnall, 28, of Rowlett, Texas.
McDonnall died Tuesday morning on a helicopter that was transporting him to a military hospital in Baghdad after four U.S. military surgeons worked for six hours to save his life, the mission board said.
McDonnall's wife, Carrie Taylor McDonnall, 26, of Rowlett, Texas, remains in critical condition, the mission board said. She is the only survivor of the attack.
Lt. Col. Joseph Piek, a spokesman for American forces in Mosul, said the five were traveling in a car on the eastern side of the city when they were ambushed.
The Elliotts were scouting the best location for a water purification project, said Michelle DeVoss of the First Baptist Church in the Raleigh, North Carolina suburb of Cary.
"They knew going into Iraq, they couldn't really share their Christian faith unless somebody asked them," said Larry Kingsley, a church deacon. "They were there in a humanitarian situation. They were people who just had a great heart for helping people out."
Iraqi police and the FBI were investigating.
Iraqi officials and a U.S. military official in Baghdad, Lt. Col. Daniel Williams, said two Germans died in the Mussayab attack. A German embassy official, however, said one of the victims may have been Dutch.
Iraqi officials said the European victims were water experts working on a development project.
The poll conducted by ABC News and several other media organizations and released Monday reveals that Iraqis are divided over whether the invasion a year ago humiliated their country or liberated it.
More than half — 56 percent — said their lives are going better than before the war, compared with 19 percent who said things are worse.
About half said they oppose the presence of coalition forces, but few want those troops to leave now.
The poll of 2,737 face-to-face interviews was conducted in Iraq from Feb. 9-28 and has a margin of sampling error of plus or minus 2 percentage points.