A senior Hamas official says the militant group will never surrender in Gaza and will fight house to house against Israel's forces. Mohammed Nazzal promises Israel heavy casualties if its forces punch deeper into Gaza. Nazzal is a member of Hamas' Damascus-based political leadership. He spoke to Syrian state television on Thursday. Nearly 700 Palestinians have been killed in the fighting after Israel launched an offensive on Hamas-ruled Gaza since December 27. Israel says it launched the air and ground attack to end rocketing by Hamas, which controls Gaza.