FALLUJAH, Iraq — Four suicide bombers tried to carry out the attack Wednesday on the Fallujah Government Center, two in trucks and two on foot, according to new information released Thursday by U.S. military officials.

Dozens of Iraqi soldiers, police and U.S. forces were wounded or exposed to chlorine from one of the truck bombs used in Wednesday’s early morning attack on the downtown compound.

Fallujah police and U.S. forces shot at the first truck bomb as it approached the compound, causing the truck to prematurely detonate, said U.S. Marine 1st Lt. Shawn Mercer, a spokesman with Multi-National Force-West. There was no chlorine in the first truck bombing, he said, and no Iraqi or U.S. forces suffered injuries from the first detonation.

However, the second truck made it through the outer perimeter of the compound, detonating near a large barrier wall next to the Iraqi Army barracks, Mercer said in an e-mail. That bomb used chlorine.

Insurgents also attacked Iraqi and U.S. forces with small-arms fire, and the two suicide bombers approaching on foot were killed when they detonated their vests during the gun battle. A third insurgent moving with the two bombers was also gunned down, according to Thursday’s news release.

The coordinated attack began at 6:33 a.m. In all, the wounded and those treated for exposure to chlorine included 53 Iraqi soldiers, four Iraqi police, 14 U.S. forces, and one civilian. Some exposed to the chlorine complained of difficulty breathing, nausea, skin irritation and vomiting.

Wednesday’s chlorine attack was the eighth launched since Jan. 28.

U.S. military officials have linked the chlorine bomb attacks to the al-Qaida in Iraq group.

The head of the Army Corps of Engineers, Gulf Region Division, said Thursday that he knew of no additional steps being taken to keep chlorine under lock and key in the wake of recent insurgent attacks using chlorine.

Speaking to reporters on Thursday, Brig. Gen. Michael Walsh explained that chlorine is used for water treatment in Iraq and is prevalent throughout the country.

“There have been some measures taken to make sure that people lock those things up a little bit more and take more accountability for it but it’s being trucked and delivered around the country to the water treatment plants and other facilities,” Walsh said.

Asked how supplies of chlorine were being secured, Walsh replied: “I think it’s the normal measures that you would take, even back in the United States, where you would store that you had purchased, just put it in your storage room and make sure that it’s locked. I’m not aware of any additional security that is going on in those particular areas.”

Reporter Jeff Schogol contributed to this report.

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