How Did 12 Marines Die in One Day?

In one of the bloodiest days of fighting since U.S.-led forces invaded Iraq a year ago, 12 Marines were killed in Ramadi, west of Baghdad — the apparent victims of a coordinated series of ambushes.

The first shots were fired just after 9 a.m. Tuesday at a small column of Marines on regular patrol in Ramadi. Additional Marines were called in.

"They assembled a quick response force, ready to go someplace else, and fighting erupted at the other end of town," said Philadelphia Inquirer photographer David Swanson, who was embedded with one of the Marine units in the city.

More fighting broke out, and soon there was fighting in four different locations. One witness said shots were fired from the city's main cemetery, near the governor's palace and in alleyways. The attacks appeared to be coordinated to hit the maximum number of U.S. forces.

"We drew heavy fire from Kalashnikovs, mortars, RPGs [rocket-propelled grenades], in a pretty substantial ambush," Swanson said.

At least three of the 12 Marines who were killed died in a Humvee, hit by small-arms fire blasting through the windshield. Many of the others were on foot, felled by snipers firing from rooftops.

"One Marine very solemnly picked up a body bag, put it on his shoulders by himself and carried it to one of the disabled Humvees," Swanson said.

Hours of Fighting

The Army was called in to help, and there was air support as well. "Pretty much anyone who was able to fight came out and fought," Swanson said.

For more than five hours, there was heavy fighting throughout the city — house to house, rooftop to rooftop.

"We would go up to the roofs and look for the enemy," Swanson said, "and they would leapfrog from house to house towards the gunfire, chasing the mortar position and the machine gun position."

By late afternoon, at least 20 insurgents were dead. Many were older men, unshaven, one wearing a flak jacket that had offered him little protection.

"It was chaotic, but the Marines pushed forward and the Iraqis retreated and pushed into houses and became farmers again, and taxi drivers, and so forth," Swanson said. "They don't wear a uniform."

Identities of Fighters Remain Unclear

Pentagon officials believe the insurgents, who numbered 60 to 100, were former regime loyalists and foreign fighters — but they're still not certain.

Secretary of Defense Donald Rumsfeld downplayed the scope of the violence in Iraq. "You say pitched battles. The number of people that are involved in those battles are relatively small," he said. "There's nothing like an army or … major large elements of hundreds of people trying to overthrow or to change the situation."

But Rumsfeld did confirm that some troops scheduled to come home in the next few weeks may be delayed, as he said, "to see the current situation through."

Reported by ABCNEWS' Martha Raddatz.