Story Highlights • Six soldiers, journalist die in roadside bombing

• 3,377 US troops killed since the March 2003

• U.S. and Iraqi forces discover bloodstained torture chamber

• Deadliest attack kills 33 at Baghdad market

Adjust font size:

BAGHDAD, Iraq (CNN) -- Nine U.S. soldiers died in Iraq on Sunday, including six killed in a roadside bombing northeast of Baghdad, the U.S. military reported.

A civilian journalist was also killed in the bombing in Diyala province. The journalist's identity was not released.

The six soldiers killed were from the Army's Task Force Lightning. Two soldiers from that unit were wounded in the same attack, the military reported.

In addition, the military reported the deaths of two Marines and another soldier who died over the weekend, bringing the U.S. toll in Iraq to 3,377 since the March 2003 invasion that toppled Iraqi dictator Saddam Hussein. In the first six days of May, 25 Americans have been killed in Iraq.

Torture chamber discovered

U.S. and Iraqi forces chasing a suspected terrorist with ties to Iran early Sunday discovered a bloodstained torture chamber and a massive amount of artillery stored in a building in Baghdad's Sadr City, the U.S. military said.

"Had that thing gone off -- when you start talking about 150 artillery shells -- the extensive damage that it could have done in killing innocent civilians in Sadr City would have been horrific," Maj. Gen. William Caldwell, a U.S. military spokesman, said at a news conference Sunday.

The building was destroyed in a controlled explosion by a U.S. military ordnance team. Video showed a massive pile of rubble, with some debris landing on nearby cars. Other vehicles had shattered windows, possibly from the impact of the blast.

There were no reports of any casualties among coalition or Iraqi security forces.

Sadr City, a densely populated Shiite neighborhood, is a stronghold of radical Shiite cleric Muqtada al-Sadr's Mehdi Army militia.

Caldwell would not reveal specific information about the "known terrorist" that was the target of the intelligence-driven raid because he was still on the run.

"As best we know, this was some kind of Shia extremist element, some sort of secret cell," Caldwell said.

Multiple bomb attacks

Twelve Iraqi police officers were killed and 11 were wounded -- in addition to two U.S. soldiers -- when insurgents attacked an Iraqi police headquarters in Samarra, just north of the Iraqi capital, on Sunday, the U.S. military said.

A Samarra police official said a suicide car bomb exploded outside the headquarters just as a curfew imposed to prevent such attacks was lifted.

The U.S. military called in reinforcements to help secure the area.

While enforcements were on their way to the area, insurgents fired upon them with small arms and rocket-propelled grenades, wounding two U.S. soldiers, the military said. A coalition vehicle was also damaged.

Throughout the day, insurgents wreaked havoc by killing at least 39 people and wounding dozens of others in multiple bomb attacks in Baghdad.

Bayaa car bomb kills 33

The deadliest attack took place in a market in southwestern Baghdad's Bayaa section around noon. An Iraqi Interior Ministry official said a bomb in a parked car exploded, killing 33 people and wounding 74 others.

The U.S. military said Iraqi police and soldiers cordoned off the area and secured the blast site.

Insurgents frequently target busy markets to produce the most carnage. Police and government officials are also prime targets.

A roadside bomb killed a police officer and wounded three others who were patrolling Baghdad's Saydia neighborhood, an Interior Ministry official said. And in Baghdad's central Mansour district, a car parked near the Labor Ministry exploded, killing at least five people and wounding 10 others, a ministry official said.

Separately, 24 bodies were found scattered across the capital Sunday, according to an Interior Ministry official.

CNN's Ingrid Formanek and Jomana Karadsheh contributed to this report.