A masked gunman shot dead two Christian brothers at their alcohol shop south of Cairo on Monday, security sources said.
The incident took place just days after attacks on a Coptic church and another Christian-owned shop also south of the Egyptian capital that killed more than 10 people, as security forces braced for attacks against the Arab world's largest Christian minority ahead of Orthodox Christmas celebrations.
The gunman used a rifle in the attack, shooting at the shop from outside after pulling up on a motorcycle, two security sources said. The attacker fled the scene afterwards.
An image on social media showed the body of what purported to be one of the victims, covered in blood from the waist down.
There was no immediate claim of responsibility for the attack.
Islamic State claimed Friday's attack on a Coptic church in Helwan, east of Giza on Cairo's outskirts and on the opposite side of the Nile river.
Egypt's large Christian minority has increasingly been targeted in recent years by Islamist militants including Islamic State, which is waging an insurgency in the north of the remote Sinai Peninsula.
Sale and consumption of alcohol in Egypt is legal, and it is sold in specialist shops or licensed premises. Some Islamists say it should be banned because it is forbidden by Islam.