BAGHDAD, Iraq (CNN) -- The man believed to be responsible for last week's rocket attack on the U.S. Army's Camp Victory was captured in an early morning raid Monday, the U.S. military said.
Iraqis on Sunday gather at the scene of a weekend truck bombing that killed 17 people, police said.
In addition to the Camp Victory suspect, three other known associates of that man were captured in the Iraq Ministry of Agriculture compound in eastern Baghdad's Rusifiya district.
The four were hiding, which prompted U.S. soldiers to enter the compound to detain them, the military said.
The attack on Wednesday killed two U.S. soldiers and wounded 38 at Camp Victory, which is near Baghdad International Airport. Two third-country nationals were also wounded in the attack, but the military did not clarify their nationalities.
"We have reason to believe that, through two intelligence-driven operations over the last few days, we now have detained all of the leadership and the key operatives of the indirect fire cell that attacked Victory Base last week," said Brig. Gen. Vincent Brooks, Multi-National Division Baghdad's deputy commanding general.
On Sunday, two local journalists and a Washington Post reporter were shot dead in an area between Tikrit and Kirkuk in northern Iraq.
Tikrit police said two journalists working for a local newspaper were killed and three security guards were wounded in the ambush.
Salih Saif Aldin, a 32-year-old Iraqi reporter working for the Post, was shot and killed in the southwestern neighborhood of Saidiya, the paper reported in its Monday editions.
"The death of Salih Saif Aldin in the service of our readers is a tragedy for everyone at The Washington Post. He was a brave and valuable reporter who contributed much to our coverage of Iraq," said Leonard Downie Jr., executive editor of The Post, was quoted as saying.
"We are in his debt. We grieve with his family, friends, fellow journalists and everyone in our Baghdad bureau."
The newspaper said he had taken a taxi from the Post's office to the neighborhood "to interview residents about the sectarian violence there between Shiite militiamen and Sunni insurgents."
The paper reported that "two hours later, a man picked up Saif Aldin's cell phone and called a colleague at the Post to say he had been shot." He was shot once in the forehead, the paper said.
The area where the reporter visited had been dominated by the Mehdi Army, the militia of Shiite cleric Muqtada al-Sadr, and police believe he was killed by Sunnis aligned with the "Awakening Council" -- the anti-insurgent tribal forces working with the United States, the paper reported.
The Committee to Protect Journalists, a group that promotes freedom of the press, said before the Sunday killings that 118 journalists had been killed as a result of hostilities in Iraq.
• A car bomb targeting families returning from a post-Ramadan festival ripped through a predominantly Sunni district of Baghdad on Monday, killing at least three civilians and wounding 25, an Interior Ministry official said. The casualties included women and children. On Sunday, insurgents targeted Shiite Muslims in separate attacks in Baghdad and Samarra that left at least 24 dead, Iraqi officials said.
• Five Iraqi youths were killed and 28 Iraqis were wounded on Monday when insurgents fired mortars at two joint Iraqi-coalition military bases in the predominantly Shiite city of Diwaniya in southern Iraq, an Iraqi Interior Ministry official said. The bases are about three kilometers (two miles) apart.
• A U.S. soldier was killed and three others wounded by a roadside bomb in southern Baghdad on Sunday, the military said. Also Sunday, a U.S. soldier died in "a non-combat related incident" in Nineveh province, northern Iraq. The latest fatalities bring the U.S. military death toll in Iraq to 3,829. The toll in October stands at 22.
• Coalition forces across Iraq killed three insurgents and detained 20 people during raids on Saturday and Sunday targeting al Qaeda in Iraq, the U.S. military said. E-mail to a friend
CNN's Jomana Karadsheh contributed to this report.