Suicide car bomb kills 4 at Iraqi checkpoint
U.S. official says Al-Zarqawi reaching out to bin Laden
CNN's Matthew Chance reports on Baghdad bombings.
Saddam Hussein samples life behind bars.
Colin Powell: Kidnappings could deter support.
BAGHDAD, Iraq (CNN) -- Four Iraqi National Guardsman died and six were wounded Tuesday when a suicide car bomb rocked a checkpoint near the eastern city of Baquba, police said.
The suicide bomber was driving a 1979 Corona, and an Iraqi man believed to be involved in the attack was arrested, police said. Paperwork in the car indicated that the owner was Sudanese.
The bomber was seen following vehicles of U.S.-led multinational forces, and the car bomb was detonated as they passed the checkpoint in the city north of Baghdad.
The wounded guardsmen were evacuated to a multinational forces facility.
Last week, 70 people and dozens more were injured in a car bomb attack in Baquba. Police said the bomber drove a Toyota minibus into a marketplace near a police station, where would-be recruits were lined up outside, and detonated the explosives.
Report on al-Zarqawi
Abu Musab al-Zarqawi has attempted to communicate with al Qaeda leader Osama bin Laden, a senior U.S. military official said Tuesday, citing "credible intelligence."
The official said al-Zarqawi, a Jordanian terrorist operating in Iraq, made the attempts to communicate within the last "few weeks."
Intelligence indicates al-Zarqawi was trying to communicate about his strategy in Iraq for the insurgency movement against U.S. and Iraqi security forces, the official said.
The official could not confirm whether the communications attempt came in the form of electronic or courier-carried messages that were intercepted.
Al-Zarqawi and his associates have taken credit for a number of deadly terror attacks and kidnappings in Iraq.
Last month a Web site message purportedly linked to al-Zarqawi warned Muslims and Arab countries against sending troops to Iraq.
The United States has put a $25 million bounty on al-Zarqawi.
One dead in Najaf fighting
Six police officers in Najaf, including three bomb experts, have been taken hostage by members of the Mehdi Army, the militia loyal to radical Shiite cleric Muqtada al-Sadr, sources from the Najaf governor's office said Tuesday.
The six were kidnapped Sunday before clashes intensified around the holy city south of Baghdad, the sources said.
The hostages were taken because one of the leading sheikhs of the Mehdi Army was arrested by police in Karbala, the sources said.
The governor's office has been in touch with a spokesman for al-Sadr in Najaf who assured them the militia members would release the hostages Wednesday, the sources said.
One source said the militia members presented no demands.
Sheikh Mahmoud al-Sudani, a Baghdad-based spokesman for al-Sadr, had accused U.S. forces of being involved in an operation at one of the cleric's two homes in the city. He did not say whether al-Sadr was inside the home.
A group from the U.S. 11th Marine Expeditionary Unit was fired on while driving past a maternity hospital during a routine security patrol in Najaf, a Marine statement said. No Marines were wounded.
A senior multinational forces official said Monday that the Marines had not surrounded any homes. He could not say if Iraqi forces had been involved in fighting at al-Sadr's home, but he said no operation had been planned.
Al-Sadr was charged by an Iraqi court in the April 2003 killing of a rival cleric, but he has never been apprehended.
Six U.S. troops die
Six members of the U.S. armed forces have died in Iraq over the past 24 hours, the coalition press office said Tuesday.
Two members of the 1st Marine Expeditionary Force died of wounds received while fighting in Al Anbar province, west of Baghdad.
Late Monday, two Task Force Baghdad soldiers were killed and two others wounded in the Iraqi capital when a homemade bomb exploded.
U.S. Central Command reported Tuesday that a Marine from the 11th Marine Expeditionary Unit died as "a result of a nonhostile gunshot wound."
The military also said that a Task Force Baghdad soldier died Tuesday in a vehicle accident.
With the deaths, 921 U.S. troops have died in Iraq since the start of the war, including 684 under hostile circumstances
Other developmentsSpecial agent Paul Arthur testified at a military court hearing Tuesday at Fort Bragg, North Carolina, that Pfc. Lynndie England said, "It was just for fun," when shown pictures of her with naked detainees at Abu Ghraib prison. England is one of seven Army reservists charged in the prison abuse scandal. (Full story)An Iraqi police chief died Tuesday from wounds he received in a roadside bomb attack, hospital officials said. Police Chief Col. Moayad Bashar was on patrol in a Baghdad neighborhood, said a spokesman for the Iraqi Interior Ministry. Three other officers were treated for their injuries.A pipeline that was ready to resume pumping from the oil fields in Kirkuk to Turkey has been attacked and damaged, an official with Iraq's Northern Oil Co. said Tuesday. The northern line, frequently targeted by saboteurs, pumps about 250,000 barrels per day. The southern Iraq oil fields deliver a daily average of 1.8 million barrels. Efforts continued Tuesday to try to free three Indians, three Kenyans and an Egyptian -- all truckers for Kuwait and Gulf Link Transport Co. who have been held hostage in Iraq. The Kuwaiti company said that negotiations with the kidnappers have resumed after talks broke down Sunday.
CNN's Alphonso Van Marsh, Kevin Flower and Kianne Sadeq contributed to this report.