The incident took place in the Helwan district on the capital’s southern outskirts and involved more than one attacker, according to the state-run news agency MENA.
Local media cited the Interior Ministry as saying two policemen had been killed in the attack on the Mar Mina church.
It was not clear if the three reported dead included the attacker, or how many attackers were involved.
Cairo’s security chief headed for the scene, local media reported. Sirens were heard in central Cairo as the incident was first reported.
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