Israel struck the southern and central Gaza Strip on Monday, following a weekend strike which killed scores of Palestinians who had sought shelter in a makeshift camp.
Mawasi on the western outskirts of Khan Younis has been sheltering hundreds of thousands of Palestinians who fled to the area after Israel declared it a safe zone.
Palestinian officials say at least 90 people were killed on Saturday and many hundreds wounded. Videos have since surfaced online from the ground filming carnage, with residents carrying the wounded and dead amid flames and smoke.
Further south in Rafah, the main focus of Israel's advance since May, residents reported renewed fighting on Monday.
Israeli forces in western and central parts of the city blew up several homes, they said. Medical officials said they recovered 10 bodies of Palestinians killed by Israeli fire in eastern areas of the city, some of which had already begun to decompose.
The military also stepped up aerial and tank shelling in central Gaza in the Al-Bureij and Al-Maghazi historic refugee camps. Health officials said five Palestinians were killed in an Israeli air strike on a house in Maghazi camp.