Gunmen in a car shot dead an Egyptian army colonel and wounded two soldiers outside a hotel in eastern Cairo on Friday, security officials said.
The attack came hours ahead of planned Islamist protests that have prompted the police and military to boost their presence in the capital and other cities.
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The identity of the assailants was not clear, but militants have killed scores of policemen and soldiers since the army overthrew Islamist president Mohamed Morsi in July last year.
Morsi's ouster and detention led to a massive crackdown on his supporters that killed hundreds of people and saw thousands jailed.
Many of the militant attacks have taken place in the north of the Sinai Peninsula where militants have pledged allegiance to the Islamic State group that controls parts of Iraq and Syria.
The group, Ansar Beit al-Maqdis, has also carried out attacks in Cairo and the Nile Valley, including an attempted assassination of the interior minister last year with a car bomb.