Cairo's Museum of Islamic Art has been badly damaged in a suicide car bomb attack on nearby police headquarters.
The museum is on the other side of Bab el-Khalq Square from the city's main security headquarters.
All the windows on the facade of the museum, which was built in 1903 and houses tens of thousands of artefacts, were blasted out.
It recently underwent an eight-year, multimillion-dollar renovation.
Antiquities Minister Mohammed Ibrahim said artefacts inside were also damaged, including a rare collection of Islamic art objects, and that the museum would have to be rebuilt.
Mr Ibrahim said the attack was carried out by two men in a pick-up truck, one of whom got out when he was stopped by police before the other man detonated the bomb.
The blasts further raise tensions a day before the third anniversary of Egypt's 2011 uprising that toppled Hosni Mubarak, and just a day after Egypt's military and security leaders marked Police Day, which depicts security forces as national heroes battling terrorism.
Islamist militants have increasingly targeted police and the military since the 3 July removal of President Mohammed Morsi by the military, but the Muslim Brotherhood he represented posted a message on Twitter in English condemning the "cowardly bombings in Cairo, express condolence to families of those killed and demand swift investigation''. There was no similar tweet in Arabic.
Islamists are trying to use Saturday's anniversary to build momentum in their campaign to "break the coup". Military supporters, in turn, aim to show broad popular support for the government and military chief Gen. Abdel-Fattah el-Sisi, the man who ousted Mr Morsi.
The office of interim President Adly Mansour vowed in a statement after the attack that it was determined to "uproot terrorism'' and said it could be forced to take "exceptional measures''. It did not elaborate.