Baghdad, Iraq ? The night air hung like a hot wet blanket over the north Baghdad suburb of Slaykh. At 9 p.m., an electrical transformer blew up, plunging the neighborhood into darkness.

American soldiers, apparently fearing a bomb attack, went on alert. Within 45 minutes, six Iraqis trying to get home before the 11 p.m. curfew were shot and killed by U.S. forces.

Anwaar Kawaz, 36, lost her husband and three of four children. “We kept shouting, ‘We’re a family! Don’t shoot!’ But no one listened. They kept shooting,” she told The Associated Press. She’s expecting another child this month.

When asked about Friday’s shootings, Lt. Col. Guy Shields, coalition military spokesman, said, “Our checkpoints are usually marked, and our soldiers are trained and disciplined. I will check on that. That is serious.”

Confronted by daily guerrilla attacks that have claimed 56 American lives since May 1, U.S. troops are on edge. Iraqis complain that many innocent people have died at surprise U.S. checkpoints thrown up on dark streets shortly before the curfew. Drivers hurrying home say they don’t see the soldiers or hear their orders to stop.

The Kawaz family left the home of Anwaar’s parents on Bilal Habashi Street at 9:15 p.m. for the 10-minute drive home. They had traveled only a half-mile when they reached the intersection where they said the American bullets took their terrible toll.

A few yards in front of them, two soldiers standing near two Humvees were shooting at the family’s white Volkswagen, she said. Two other soldiers near a Humvee to the right of the car also fired, she said.

Witnesses told the AP one of the soldiers fell to the ground screaming in pain, apparently a victim of friendly fire.

Lt. Sean McLaughlin, stationed at a base near Slaykh, could only express sympathy, although he said his unit was not involved.

“No one feels worse than us. We want to build a safe Iraq for the Iraqis. It’s a difficult situation here,” McLaughlin said.