At least five Israeli soldiers have been killed on Monday.
The Associated Press news agency reported that nine Israeli soldiers had been killed in separate attacks.
Earlier, Israel confirmed five soldiers had died on Monday – one inside Gaza and four in a mortar attack along the border.
Another 10 were injured when a mortar shell hit the Eshkol district in southern Israel.
Israeli prime minister Benjamin Netanyahu warned of a prolonged offensive in Gaza.
“I’ve said it before and I’ll say it again, we must expect a long-lasting operation. We’ll continue to work with strength and determination until we achieve our goal which is to protect our citizens, protect our armed forces and, finally, to protect our children.”
The Israeli army has continued operations to destroy tunnels which it calls “terror tunnels”. It says are used by Hamas and remain a huge threat to Israeli security.