JENIN, West Bank –– The snapping of a tank tread, rather than an explosion, produced the loud noise that spooked Israeli soldiers who then opened fire on nearby Palestinians, killing a mother and her two preschool children, the Israeli military said Monday.

The military initially said a mine went off near the tank on Sunday. Searching for Palestinians they believed might have placed the explosives, members of the tank crew opened fire on nearby Palestinians.

The tank fire killed a 30-year-old Palestinian woman farmer and her children, ages four and six, who were picking grape leaves in the area, southwest of the Palestinian city of Jenin, Palestinian witnesses said.

The army expressed regret for the killings and said it would investigate the shooting. Military investigators found no traces of a bomb in the area, and an inspection of the tank found that its tread had come loose, causing the sound of an explosion that misled the crew, an army spokesman said Monday.

Mohammed Zakarneh, his wife Fatma and two of their children, 4-year-old Abir and 6-year-old Bassel, had set out at dawn Sunday for the vineyard. The family made the trip daily from their town of Qabatiya, just a short ride away.

On a nearby road, the tread snapped off the Israeli tank. Searching for those who might have placed a bomb for them to drive over, soldiers came upon the Palestinian family.

Zakarneh said he saw the tank's machine gun swivel toward them and fire. In a moment of horror, he looked at his little girl, Abir – bullets had pulverized her small face. His wife lay bleeding from her head and neck. Bassel, was barely breathing; he later died, Zakarneh said.

Zakarneh said he wept and tore at the earth, throwing soil into his face in grief. One of the soldiers who came to him fainted at the sight of the dead girl.

Other soldiers cuffed Zakarneh's hands and questioned him with seven others they rounded up, Zakarneh said.

Some three hours later, Zakarneh was allowed to go. An Israeli officer apologized to him in Arabic, saying the soldiers had killed his family by accident.