The Israel Defense Force said it struck over 200 targets in Gaza overnight.
More than 1,200 people have been killed in Gaza since Israel launched its air strikes on Saturday, according to the Palestinian Health Ministry.
A similar number of people in Israel are now thought to have been killed in the multiple attacks by Hamas at the weekend.
US Secretary of State Antony Blinken has arrived in Israel - the White House is warning other regional countries not to "take advantage" of the situation.