DHAHRAN, SAUDI ARABIA, FEB. 1 -- In ground fighting on the Saudi-Kuwaiti border this week, allied forces mistakenly dropped cluster bombs on the edge of a U.S. military encampment and took part in an armor and artillery battle so intense that forward observers sometimes could not tell Iraqi weapons from allied ones, according to battlefield accounts.

The U.S. military today was investigating the possibility that U.S. forces accidentally killed some of their own Marines during border fighting Tuesday night.

These first significant land battles along the border, coming after 16 days of war fought from the skies with computerized weapons and videotaped bombardments, quickly demonstrated the complexities of the far more chaotic and imprecise ground combat allied troops are likely to face in the weeks ahead.

Capt. Joe Fack, one of a handful of Marines who entered the Saudi coastal town of Khafji soon after it was overrun by Iraqi troops and directed allied fire during attacks that eventually routed most of the Iraqis two days later, described a whirlwind of combat in which telling friend from foe often was dangerously difficult.

"Tanks were firing at tanks," Fack said. "But everything was so confused. I didn't know what unit was which and who was firing at who."

During fierce fighting between Iraqi and allied forces farther west along the border before dawn today, two U.S. bombers, in attacks three minutes apart, dropped eight cluster bombs near a U.S. Marine battalion's camp. Slivers of shrapnel from the bombs landed within 15 yards of a spot where Marines would have been sleeping, while the bombs -- which release more than 200 individual explosives each -- scorched large patches of sand within 220 yards of the Marines' command post, Maj. Bob Weimann, 40, of Woodbury, N.J., told news media pool reporters. No injuries were reported.

"It looked like a thousand Fourth of July sparklers lit up at once," said one Marine who scrambled for cover during the 1 a.m. strike.

The U.S. troops were confused in the chaotic minutes following the aerial attack, Weimann said: "But, with our air supremacy, I assumed it was friendly fire. . . . Someone got the wrong 'lat-long,' " he said, referring to the latitude and longitude coordinates used to identify targets.

The debris left by the bombs bore marks identifying them as U.S. weapons, and Marines today awaited the arrival of explosives teams to clear their sandy camp of unexploded duds, officials told reporters.

"People have taken it in stride as an unfortunate accident of war that could have been worse," Weimann said.

"Getting wasted by our own guys would be the ultimate waste," said one sergeant. "But with all the thousands of sorties being flown I suppose things like this are going to happen."

U.S. military officials are investigating reports that some of the 11 Marines killed during what one commander described as "hellacious" fighting near the border Tuesday night may have died when a missile fired by a U.S. aircraft slammed into their light armored vehicle.

"We're saddened and disappointed" at the prospect that some of the Marines may have been killed by "friendly fire," Lt. Col. Jerry Humble, operations officer for the 1st Marine Division, told reporters. "But historically there's always casualties by friendly fire in close battles, because it's a fight for your life."

Humble said that at some points during the fierce nighttime battle, U.S. Marine and Iraqi forces exchanged fire from as close as 25 yards.

"There are times you don't know from what direction the fire came," Pentagon spokesman Pete Williams said in Washington. "There is the possibility we may never know" who fired the shots that killed the Marines.

Twelve Marine reconnaissance team members who found themselves trapped for two days in the duel for Khafji, a coastal town about six miles inside Saudi Arabia that had been evacuated before the war began, related vivid accounts of the "fog of war" that led to moments of chaos and confusion during the battle.

The two six-member teams had driven into Khafji to serve as spotters for allied air and artillery attacks. One Marine said the teams did not realize the town was being invaded until he saw a helmeted head atop an armored personnel carrier rolling down the street.

"I never expected that kind of fear," said Lance Cpl. David McNamee, 19, a Falls Church, Va., native who scurried from hiding place to hiding place during the shootout, which lasted until Saudi and Qatari troops, backed by U.S. artillery and planes, retook Khafji on Thursday.

At one point Iraqi troops parked armored personnel carriers outside the building where McNamee and other Marines hid. Throughout the night, the Americans listened as the Iraqi soldiers yelled and laughed, McNamee told news pool reporters.

"I'd be lying if I didn't say that dying hadn't crossed by mind," added Cpl. Chuck Ingraham of New Orleans. "We were shaking for two days from cold and fear. I didn't eat, I hardly drank any water and hardly got any sleep."

Other members of one of the units said they saw Iraqis looting what appeared to be a supermarket. But Cpl. Jeff Brown of Cincinnati told a pool reporter that the Iraqis "were well-disciplined and good troops."

At one point, after the Marines had moved to a four-story apartment building, Iraqi troops entered the first floor of the apartment complex, glanced around, but did not climb the stairs -- which the Americans had rigged with Claymore mines.

"They sure would have had a rude awakening if they had come up after us," Brown said. "We would have blown them to hell."

During the battle, the teams directed artillery fire nearly atop their own positions to protect their location and destroy nearby Iraqi armored vehicles, according to accounts relayed to reporters. Brown was wounded slightly in the leg when an American cluster shell, timed to explode in the air, sprayed shrapnel across his hiding place.

The teams communicated with Marine artillery units south of the town through brief radio exchanges, always fearful that the Iraqis could detect their broad-casts.

As Saudi and Qatari forces battled Iraqi tanks and troops Thursday in a successful bid to retake the city, U.S. warplanes and artillery staged two major assaults on the town in an effort to free the trapped Marines. Finally, after two days of fighting, one team ran several hundred yards to allied lines, and the other team sped out of town in two vehicles called "humvees," one of which wobbled on a tire punctured by shrapnel.

The allied forces pushed Iraqi troops out of the deserted village, and by this morning, only sporadic sniper and artillery fire echoed through the largely deserted streets of the town.

The Saudi army commander, Gen. Khalid bin Sultan, said 30 Iraqis were killed, 33 wounded and 400 taken prisoner. U.S. officials said more than 500 Iraqis were captured.

Destruction was evident throughout the village today, according to reports filed by pool reporters taken into Khafji.

The charred skeleton of a Saudi soldier was seared to the driver's seat of a smoldering armored personnel carrier, while the blackened corpse of a second soldier stuck halfway out of the vehicle. Nearby, the body of an Iraqi soldier, his arm draped over his face, lay wrapped in a blue-and-white blanket.

The blackened hulks of Saudi and Qatari armored personnel carriers served as smoking reminders of the failed attempts to recapture the city in the first day of fighting. Artillery shells and unexploded ordnance littered the streets, according to reports.

This article contained information derived from news pool reports.

Wednesday

Early morning: Iraqi forces invade the Saudi town of Khafji. Thursday

2:30 a.m.: Saudi and Qatari forces counter-attack.

7:30 a.m.: Saudi forces engage eight Iraqi armored units withdrawing to the north. All eight vehicles are destroyed.

10:30 a.m.: Saudi forces engage Iraqi troops moving south along the Coast Road. Two Iraqi tanks are destroyed. The enemy forces withdraw to Kuwait.

2 p.m.: Khafji is liberated. Saudi forces set up defensive positions north of the city.

2 to 5 p.m.: Saudi forces continue to engage enemy tanks with artillery and coalition air power north of Khafji. Enemy forces eventualy withdraw to the north. REPORTED IRAQI LOSSES

Seven tanks destroyed

Nine armored personnel carriers destroyed.

30 killed in action, according to Saudi officials.

33 wounded in action, according to Saudi officials.

At least 500 captured and made prisoners of war, according to U.S. officials. REPORTED SAUDI LOSSES

15 killed in action.

32 wounded in action.

Four missing in action.

Three tanks (two of which will be repaired).

One multiple launch rocket vehicle.