Attacks continued overnight in Gaza, with Israel launching several air and naval bombardments and the Palestinians firing a number of rockets into Israel.
The Palestinians said that a vehicle which was distributing water to local residents was targeted by an Israeli airstrike.
Health officials in Gaza say 72 people have been killed and hundreds more wounded.
Three civilians in Israel have also lost their lives.
On the border, Israeli tanks and infantry have massed as officials say they are ready to widen the offensive.
While both sides have spelt out conditions for a truce, efforts are underway to broker a ceasefire.