There has been a large car bomb explosion in the Egyptian capital Cairo, near the city’s police headquarters, officials say.
There are reports of casualties. The AFP news agency has reported one person has been killed.
Eyewitnesses speak of smoke rising over the city centre, and there are reports of gunfire after the blast.
Newspaper reports say the front of the police building has been damaged and emergency services are at the scene.
The blast comes on the eve of the anniversary of the beginning of the 2011 uprising that led to the removal of the country’s long-serving ruler Hosni Mubarak.
Correspondents say that the banned Muslim Brotherhood and its partners are planning protests after Friday prayers across the country, the latest in a series of regular demonstrations against the overthrow in July of Islamist President Mohammed Morsi.
Brotherhood supporters are also angry over recent moves to introduce a new constitution.