The Arab satellite TV network al-Jazeera aired a videotape Sunday from a group threatening to kill a U.S. Marine it claimed to have captured by luring him from his post, and two Americans and four Iraqi boys were among those killed across the country in a succession of attacks.

A Defense Department employee was killed when rifle shots were fired at a cargo plane taking off from Baghdad's main airport, and a U.S. soldier was killed in a rocket attack on a base on the outskirts of the city. The Iraqi boys were killed when they were hit by mortar shells that apparently missed their target.

Late Sunday, al-Jazeera broadcast a video showing a blindfolded man in military fatigues as well as photos that appeared to identify him as Cpl. Wassef Ali Hassoun. In a statement, the U.S. military said that Hassoun, a member of the 1st Marine Expeditionary Force, had been missing from his unit since June 21, but it could not confirm that he had been taken hostage. Al-Jazeera said a group calling itself Islamic Response claimed that it had captured the Marine. Unlike videos of two previous hostages who were beheaded, the broadcast tape had no audio.

Earlier Sunday, another Arab satellite television network, al-Arabiya, broadcast a video of a Pakistani hostage whom kidnappers identified as a driver for the U.S. military. A group led by Abu Musab Zarqawi, a Jordanian who has asserted responsibility for much of the recent violence in Iraq, announced Saturday that three Turkish workers were also being held.

On Sunday, Turkey rejected demands to withdraw its citizens from Iraq, which the kidnappers wanted. Turkey has no troops in Iraq, but Turkish contractors and employees work in the country. The kidnappers, believed to be part of the same group that beheaded a South Korean and an American, said they would kill the hostages if the Turkish workers were not withdrawn by Tuesday night.

Also, two separate shellings of the Green Zone, the heavily guarded U.S. compound in central Baghdad, resulted in no reported injuries. But the day's violence underscored the fragile security situation in the country, as the U.S. transfer of political authority to the interim Iraqi government on Wednesday approaches.

Iraqi police said they had arrested three men in Baghdad who were carrying rockets and weapons en route to attacking a police station. Separate attacks in the northern cities of Mosul and Irbil killed two people and injured five Kurdish militiamen, according to wire service and local reports.

The boys killed Sunday were swimming along a bank of the Tigris River as the heat from the sweltering 108-degree day began to ebb when two mortar shells apparently aimed at the U.S. compound across the river fell short of their target. One of the shells created a crater at the water's edge. Hazim Ghafif, 24, who makes his living washing cars along the riverbank, said he stopped a passing car and carried youths, who he said appeared to be about 6 or 7, to be transported to the hospital. Two older boys were killed by the blast, he said. "This is violence and chaos, nothing else," Ghafif said. "Those against the Americans feel they have to do it because of the approaching end of American authority."

But the anger toward the occupation also was evident at the site, where two empty shoes and a pool of blood on the riverbank marked the scene. "The Americans did this," shouted a man waving a bloody shirt. "They shot the shells."

In the same attack, smoke was seen rising over the Green Zone, as it had during a similar mortar shelling in the morning. U.S. military officials have declined to provide access to the attack sites. The interim Iraqi government has vowed to stop the violence. The interim prime minister, Ayad Allawi, said in successive television interviews over the weekend that the scheduled date for national elections, Jan. 31, could slip by one or two months if the security situation did not improve.

Late Sunday afternoon, small arms fire hit an Australian military C-130 cargo plane as it lifted off from Baghdad International Airport. Aircraft landing and departing from the airport often maneuver to minimize exposure to shoulder-held missiles or small arms fire from the surrounding neighborhoods. The gunfire did "no significant damage" to the airplane, according to a statement by the military, but a Defense Department employee was hit. The plane landed so medical treatment could be provided, but the victim died. The military declined to give more information.

L. Paul Bremer, the U.S. civilian administrator of Iraq, visited the southern city of Hilla, where two car bombs killed dozens of people Saturday night. Local hospital officials put number of dead at 31. U.S. military officials first said the death toll was 40, then revised it to 23.

"The people who did this are enemies of Iraq, not enemies of the occupation," Bremer said.

Also on Sunday, Allawi confirmed reports that former Iraqi president Saddam Hussein would be charged in an Iraqi court in "a week or two." U.S. officials have said Iraq will press charges against Hussein but that he will remain in U.S. custody. A special Iraqi tribunal is seeking to try Hussein for crimes committed during his dictatorship, including for the deaths of 300,000 people.

[On Monday, the U.S. military announced that a Marine was killed in action Saturday in Anbar province west of Baghdad, according to the Reuters news agency.]

This image from a video broadcast by the al-Jazeera network shows a man identified on the video as Cpl. Wassef Ali Hassoun, a U.S. Marine who has been missing since June 21.