An Egyptian policeman has been killed in a bomb blast next to a checkpoint on a bridge in Cairo.
The explosion, in the upmarket Zamalek district, injured several more people on the May 15 bridge.
The policeman was ripped apart by the blast, which left a crater in the ground, officials and witnesses said.
No group has said it carried out the attack, but violence by Islamist groups has increased since the overthrow of President Mohammed Morsi in 2013.
There was another bomb in Cairo on Saturday but it caused no casualties.
The Ajnad Misr group last week said it was behind an explosion at Cairo University that injured eight people.
Much of the worst violence is in the Sinai peninsula, where dozens of soldiers and police have been killed in recent months in attacks by militants pledging loyalty to Islamic State.
The overthrow by the military of Mr Morsi, a leader of the Muslim Brotherhood, was followed by the suppression of his supporters.
Hundreds have been killed and thousands jailed since President Abdul Fattah al-Sisi, former head of Egypt’s armed forces, came to power.