Hamas installations throughout the Gaza Strip were attacked on Saturday, the Jerusalem Post reported.

The BBC says that Israeli F-16 bombers killed and injured scores of people.

Medical staff and Hamas officials said at least 140 people were killed when missiles hit security compounds and militant bases across Gaza.

Minutes after the operation was launched, Sky News reported that there were "many" casualties in the attacks. Footage showed a number of wounded people laying on the ground near the Hamas police headquarters in the Strip.

At least four people were killed and seventy injured in the airstrikes, Palestinian medical official Moiwa Hassanein said.

Earlier, a Kassam fired from Gaza hit a building on a Sha'ar Hanegev kibbutz.

Damage was caused to the building, but no casualties were reported in the attack.

On Friday, two Palestinian girls were killed when a rocket fired by Palestinian terrorists landed short of its Israeli target.

According to witnesses, the girls were immediately killed after sustaining a direct hit. Gaza Health Ministry official Dr. Moiaya Hassanain identified the two victims as 5-year-old Hanin Abu Khoussa and her 12-year-old cousin, Sabah Abu Khoussa. Three other young people were wounded, Hassanain said.

Hamas announced that it planned to investigate the incident which occurred in the northern Gaza Strip town of Beit Lahiya.

Also Friday, Israel agreed to treat a 35-year-old Palestinian who was also wounded by a rocket fired from Gaza towards Israel.

The man was evacuated to Tel Aviv's Ichilov Hospital in serious condition after being transferred from a Palestinian ambulance to a Magen David Adom ambulance at the Erez Crossing.

The man was wounded in a Kassam attack on Tuesday, and was since then treated in a Gazan hospital before medical officials decided to move him to Israel for treatment.

Twenty-five mortar shells have been fired into Israel since Thursday night.