Meanwhile, Palestinian authorities in Gaza say more than 1,200 have been killed since Israel's airstrikes and supply siege began. Gaza is also lacking electricity after its only power station ran out of fuel. Food, water and medical supplies are also running low.
The White House has said the US is working with Israel and Egypt in an attempt to set up safe corridors for civilians in Gaza. Egypt's president also says he is intensifying efforts to contain the conflict.
The Rafah crossing on the Egyptian border was seen as a possible route for Gazans trying to flee, but it is now closed.