Meanwhile, U.S. troops killed five suspects and captured 30 others in a raid in Iraq's western Anbar province, a day after police uncovered 17 decomposing corpses beneath two school yards in the provincial capital.
The U.S. military also announced a discovery made nearly a week earlier - 3,000 gallons of nitric acid hidden in a warehouse in downtown Baghdad. U.S. forces found the acid - a key component in fertilizer but also explosives - during a routine search operation last Thursday, the military said.
The U.S. raid took place early Wednesday near Karmah, a town northeast of Fallujah, which lies 40 miles west of Baghdad.
American forces raided a group of buildings suspected of being used by militants, and found explosives inside one of them, the military said in a statement. A helicopter was called in, and dropped precision-guided bombs on the cluster of buildings, it said.Meanwhile, troops came under fire and reacted in ''self-defense,'' the statement said - killing five Iraqis and wounding four others.
The wounded were taken to a military hospital and remained in U.S. custody. Twenty-six others were captured as well, the military said.
Later, the military issued another statement that one suspect was killed and eight captured in two more raids Wednesday north of Baghdad. Some of the suspects were believed to be linked to al-Qaida in Iraq, and to a militant cell that has used chlorine in car bombings, the statement said.
The bodies found a day earlier at school yards in Ramadi, Anbar's provincial capital, were discovered after students and teachers returned to the schools a week ago and noticed an increasingly putrid odor and stray dogs digging in the area, Police Maj. Laith al-Dulaimi said.
He said one body had not yet been recovered from a separate burial site behind one of the schools because authorities feared it was booby-trapped with a bomb.
Ramadi had been a stronghold of Sunni insurgents and al-Qaida fighters until recently, when the U.S. forces in the region and the Iraqi government successfully negotiated with many local tribal leaders to split them off from the more militant insurgent groups.
Thousands of young Sunni men have joined the police force in Anbar province and have taken up the fight against the Islamic State of Iraq, the umbrella organization that includes al-Qaida.