Egypt has seen increased attacks on security forces since the army ousted Islamist President Mohammed Morsi in July 2013.
Most incidents have been confined to the restive Sinai peninsula.
There, the authorities are battling jihadists who have pledged loyalty to the co-called Islamic State (IS) group. IS`s local affiliate says it was behind the crash of a Russian jet in Sinai, which killed all 224 people on board.
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