BAGHDAD, Iraq – Four of the five U.S. soldiers killed in a sophisticated attack in southern Iraq last week were shot after they were captured, handcuffed and driven miles away by gunmen who appeared to have detailed information about their target, U.S. and Iraqi officials said Friday.

“The attackers went straight to where the Americans were located in the provincial government facility, bypassing the Iraqi police in the compound,” Lt. Col. Scott Bleichwehl, a spokesman for U.S. forces in Baghdad, said in a statement. “We are looking at all the evidence to determine who or what was responsible for the breakdown in security at the compound and the perpetration of the assault.”

The U.S. military announced last week that five soldiers in Karbala died fending off the Jan. 20 attack on a provincial security building, but details of what happened were not released.

However, hours after an Associated Press report cited unnamed U.S. and Iraqi sources in recounting the attack and killings, the military on Friday issued a detailed statement on the incident that said the four soldiers were found dead or dying near abandoned vehicles in a neighboring province south of Baghdad.

The account of the attack provided by the military suggests both a dramatic breakdown of security in the relatively safe southern province as well as increased skillfulness and capacity on the part of armed groups.

“The precision of the attack, the equipment used and the possible use of explosives to destroy the military vehicles in the compound suggests that the attack was well-rehearsed prior to execution,” Bleichwehl said.

U.S. soldiers and their Iraqi counterparts were at a provincial security headquarters discussing safety for pilgrims participating in an annual religious ceremony when the gunmen – dressed in U.S. Army-style combat uniforms and driving at least five sport-utility vehicles – made their way past checkpoints and stormed the building at around 5 p.m.

“The armed militants wore American-looking uniforms and carried U.S.-type weapons, convincing Iraqi checkpoints to allow their passage,” the statement said.

Once they were inside the compound the fighting broke out between the gunmen, estimated at no more than a dozen, and U.S. soldiers. Small-arms fire erupted and grenades exploded. One soldier was killed and three wounded by a hand grenade thrown into the compound’s main office, which includes the headquarters of the provincial police chief.

“The Iraqis in the meeting were not harmed or even touched,” said an Iraqi military official.

Explosions damaged several U.S. military Humvees, disabling the vehicles and forcing the soldiers to take cover. The attackers pulled back, the statement said, taking four U.S. soldiers with them.

According to U.S. and Iraqi officials, not only did the gunmen manage to evade security forces and enter the building, they drove the captured soldiers from Karbala dozens of miles to Babel province, confidently whizzing past at least one checkpoint.

“The vehicles did not stop at checkpoints, they drove right through them,” said an Iraqi military officer, speaking on condition of anonymity.

The military said suspicious Iraqi police officers pursued them. Iraqi security officials said American and local forces encircled the area and established a curfew.

Residents could hear heavy gunfire and see flares light up the sky as Iraqi forces, including members of Hillah’s Scorpion Brigades, searched the area.

The Iraqi police eventually found the captured U.S. soldiers, dead or dying, as well as five abandoned SUVs, U.S. Army uniforms, boots, radios and sophisticated machine-guns near the Sunni towns of Mahawil and Albu Alwan in northern Babel province.

“Two soldiers were found handcuffed together in the back of one of the SUVs,” the U.S. military statement said. “Both had suffered gunshot wounds and were dead. A third soldier was found shot and dead on the ground. Nearby, the fourth soldier was still alive, despite a gunshot wound to the head.” The soldier died as Iraqi police rushed him to a nearby hospital.