Six people were killed and three injured on Friday morning in clashes that erupted between police and pro-Muslim Brotherhood protesters in the working class district of Talbiya in Giza, state news agency MENA reported.
According to health ministry sources quoted by MENA, the casualties were all supporters of the Brotherhood.
The clashes erupted following the Eid Al-Fitr prayers which took place on Friday morning, as the Brotherhood supporters held minor protests and clashed with other local residents.
Police intervened and arrested 15 people, according to a security source.
On Thursday, social media pages that represent former president Mohamed Morsi, who is in prison, published a message purporting to be from him in which he called on his supporters to "continue the revolution.
The Talbiya district, located in Greater Cairo, has seen a number of clashes between pro-Brotherhood supporters and police since the ouster of Morsi in 2013.