A mother threw her baby out a car window in a desperate attempt to save its life as a huge construction vehicle bore down on her car, and another baby's mother was killed Wednesday when a Palestinian worker went on a rampage on Jerusalem's main street.

The attacker aimed his heavy vehicle to crush cars, buses and pedestrians, killing three people and wounding at least 45 before he was shot dead by security officers.

A young mother watched in horror as the vehicle charged straight at her vehicle and then instinctively threw her baby out the car window to save her, Israeli media reported.

The baby was unharmed but the mother was injured in the collision, Channel 2 TV reported.

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Another mother was killed, but her infant survived.

Medics said they thought they had evacuated all the wounded from an overturned bus and then they heard a baby crying, Israeli media reported.

They found a 5-month-old baby girl stuck under a seat and rushed her to hospital. As the hours ticked by and nobody came forward to claim the baby, it became apparent that her mother had been killed in the attack.

"This poor, innocent baby is lucky to be alive. The sad thing is she is far too young to comprehend her own tragedy," said Tzipi Lefler, a social worker taking care of the baby.