IS claims deadly attack in Egypt Suez Canal city
"A cell of soldiers of the caliphate managed to attack an Egyptian police roadblock... with a machine gun," the jihadist group's Amaq news agency said.
Three Egyptian policemen were killed in the attack, the first of its kind in nearly three years in mainland Egypt, which has largely been spared the deadly insurgency in the nearby Sinai peninsula.
In the past few years, attacks against Egyptian security forces have been concentrated in the Sinai, where jihadists affiliated with IS operate.
Eleven soldiers were killed on May 7 in an attack in western Sinai.
Days later, another five soldiers and seven jihadists died when the army was attacked in the peninsula.
Ismailia is one of the key cities overlooking Egypt's Suez Canal, a vital waterway between Asia and Europe that sees about 10 percent of the world's maritime trade.