NEAR KARBALA, Iraq, March 31 -- As an unidentified four-wheel drive vehicle came barreling toward an intersection held by troops of the Army's 3rd Infantry Division, Capt. Ronny Johnson grew increasingly alarmed. From his position at the intersection, he was heard radioing to one of his forward platoons of M2 Bradley Fighting Vehicles to alert it to what he described as a potential threat.

"Fire a warning shot," he ordered as the vehicle kept coming. Then, with increasing urgency, he told the platoon to shoot a 7.62mm machine-gun round into its radiator. "Stop [messing] around!" Johnson yelled into the company radio network when he still saw no action being taken. Finally, he shouted at the top of his voice, "Stop him, Red 1, stop him!"

That order was immediately followed by the loud reports of 25mm cannon fire from one or more of the platoon's Bradleys. About half a dozen shots were heard in all.

"Cease fire!" Johnson yelled over the radio. Then, as he peered into his binoculars from the intersection on Highway 9, he roared at the platoon leader, "You just [expletive] killed a family because you didn't fire a warning shot soon enough!"

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Dealing with the gruesome scene was a new experience for many of the U.S. soldiers deployed here, and they debated how the tragedy could have been avoided. Several said they accepted the platoon leader's explanation to Johnson on the military radio that he had, in fact, fired two warning shots, but that the driver failed to stop. And everybody was edgy, they realized, since four U.S. soldiers were blown up by a suicide bomber Saturday at a checkpoint much like theirs, only 20 miles to the south.

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