"You just (expletive) killed a family because you didn't fire a warning shot soon enough," US Army 3rd Division Captain Ronny Johnson was heard shouting over the radio to his men after the shooting stopped Monday, the daily said.

Ten Iraqi civilians, including five children, were killed by the 25mm cannon fire, another man was so badly injured he was not expected to live, while four other survivors escaped largely unhurt, Johnson's company told the Post.

Navy Lieutenant Commander Charles Owens, a US military spokesman in As-Saliyah, Qatar, put the death toll at seven, saying that 13 women and children were inside the Iraqi vehicle and that four people escaped unharmed.

The shooting occurred at a checkpoint at Najaf, 150 kilometers (95 miles) south of Baghdad, on Monday afternoon, Owens said, adding that the Iraqi vehicle failed to stop despite repeated warning shots fired by US troops.

The Washington Post said Johnson was in position at the intersection when he was heard radioing to one of his forward platoons of M2 Bradley Fighting Vehicles to stay alert as an unidentified four-wheel drive vehicle approached.

"Fire a warning shot," Johnson told his men as the vehicle kept coming.

He followed with another, more urgent order to shoot a machine-gun round into the vehicle's radiator.

"Stop (messing) around," Johnson then yelled at his men when he saw no action had been taken, according to the daily.

"Finally, he shouted at the top of his voice, 'Stop him, Red 1, stop him!'"

About half a dozen loud reports followed, with Johnson shouting "Cease fire," over the radio, the daily said.

Johnson's comment that the civilian deaths were due to warning shots fired too late, seem to be disputed by unnamed US soldiers The Washington Post said "accepted the platoon leader's explanation to Johnson over the radio that he had, in fact, fired two warning shots, but that the driver failed to stop."

Lieutenant Owens said an investigation had been opened into the shooting.

A written statement issued by the US Cental Command later said "initial reports indicate the soldiers responded in accordance with the rules of engagement to protect themselves."

"In light of recent terrorist attacks by the Iraqi regime, the soldiers exercised considerable restraint to avoid the unnecessary loss of life."

The shooting came as US forces in Iraq were on an increased state of alert following a suicide car bombing, also near Najaf, on Saturday that killed four US soldiers also from the US Army's 3rd Division.

SPACE.WIRE