“I just turned my head, saw the flash of white, saw the warm red running down my hand,’’ the Fond-du-Lac, Wis., native recalled at a hospital on Thursday. “I thought it was the end. I saw that round hit. I thought I was done.’’

They call it the Turkey Shoot, and they are the targets. Every day, Marines trying to keep critical supply lines open to forward units heading toward Baghdad run a gauntlet through the strategic crossroads city of Nassiriyah — over one bridge, up a few miles and then over another bridge. If they make it without getting shot at, they’re lucky.

The passage, about 100 miles north of the Kuwait border, has become perhaps the most treacherous few miles in Iraq. A contingent of about 120 Marines trying to make it to the first bridge Wednesday came under fire from assault weapons and rocket-propelled grenades; some 15 of their Humvees and seven-ton trucks were destroyed and more than 60 of the Marines were wounded.

“Nassiriyah was supposed to be a six-hour fight,’’ said Gunnery Sgt. Tracy Hale, 32, of Philadelphia, who was injured in the battle and brought to the field hospital here. “It’s already been five days. Five days of nonstop, 24-hour fighting.’’

From the perspective of commanders running the war, Nassiriyah has proved to be a strategic success. The Marines captured two vital bridges and have moved hundreds of tanks, armored vehicles, fuel trucks, Humvees and other military vehicles across them in the last few days to build up forces heading toward Baghdad.

From the perspective of Marines fighting the war, however, Nassiriyah has proved to be a nightmare. The Marines leapfrog forward across the bridges, a new unit coming to relieve the one that heads across, constantly moving to maintain momentum. With so many civilians nearby, it’s never clear who is friend and who is foe.

“Each unit takes its turn being sacrificed,’’ said Sgt. Chris Merkle, 31, from Irvine, Calif., who made the run the other day. “Everybody gets torn apart the same way.’’

Nassiriyah became a critical juncture early on in US war planning because of the crossings over the Euphrates River. It became a killing field over the weekend with a pair of grisly disasters for US troops. An army convoy that made a wrong turn ran across an Iraqi ambush, with 12 soldiers killed or captured. In a separate incident, at least nine Marines died in the fighting. A military source said Thursday that preliminary indications suggested they may have been killed by fire from an A-10 Thunderbolt tank killer trying to help them.

Lt. Gen. James Conway, the top Marine commander in the region, personally visited Nassiriyah the next day to inspect the battlefield and came close to two or three gun battles himself, according to his chief of staff, Col. John Coleman. “It’s the wild west there,’’ Coleman said. “We control what we want to control, but it’s not a very safe place.’’

Iraqis mounting the attacks appear to be a mix of Saddam’s Fedayeen, a paramilitary group loyal to President Saddam Hussein, and regular army soldiers. Marine officers said they’ve found bodies of regular army soldiers with gunshots to the head, an indication, they believe, that the Fedayeen or Republican Guard commanders have been forcing soldiers to fight and killing those who don’t.

While Republican Guard commanders apparently have come to Nassiriyah to organize the attacks on the Marines, they don’t stay once the fighting begins, according to US military intelligence. The fighters themselves generally dress in civilian clothing, making it harder to distinguish them from innocents. For the Marines driving through every day, it’s been hard to know how or where to concentrate their firepower. With many of the attackers out of uniform and hiding behind civilians, Marines say they have had to refrain from returning fire, according to several interviewed Thursday at an 80-bed field hospital opened here in southern Iraq the day before.

“It’s a turkey shoot,’’ said Merkle, a reservist who normally works as a Fed-Ex delivery man. “It’s not an actual engagement. You’re just receiving fire and trying to get through as fast as you can.’’

At one point, Merkle recalled, some Iraqi fighters pretended to surrender. “As they’re surrendering, the Marines said, ‘Put down your weapons, put down your weapons,’’’ he said. “They ran back into the building and pushed the kids out the windows and doors. The kids started running because they were scared and then the men ran out shooting.’’