Israeli warplanes have hit 150 targets since the start of the retaliatory strikes, a Palestinian security source tells the BBC.
This included several compounds where Hamas leaders were believed to be residing.
Twenty-four Palestinians, including two women and four children, have been killed since midnight (21:00 GMT).
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More than 250 civilians have been killed in total, according to Palestinian officials.
(Editor: Nkoli Omhoudu)
