An Egyptian police officer was killed when a bomb targeting a traffic police kiosk exploded in Cairo, security officials said.
The explosion rocked the busy Lebanon Square in Cairo's Mohandessin district on Friday, killing Mohammed Gamal Eddin, Egypt's interior ministry reported.
A security official told the Associated Press news agency that the bomb was planted inside the traffic post and it exploded around 10pm (08:00 GMT).
Three other people were injured in the attack including a senior police officer, the official said.
An armed group, Ajnad Misr, has claimed responsibility for the attack. The group said in a statement on Saturday that its fighters had monitored the police checkpoint the square before detonating the bomb.
Ajnad Misr, or Soldiers of Egypt, formally announced itself in January saying it would target "criminal elements" in the military-backed government. The group has claimed at least six attacks since then, including explosions outside Cairo University which killed a police brigadier-general and one other person earlier this month.
Egypt has been hit with violence since the military overthrow of Islamist President Mohammed Morsi last year.
Official figures show that more than 500 people, mostly policemen and soldiers, had been killed in bombing and shooting assaults by rebels since the July ouster.
On Tuesday, two bomb blasts wounded six people including at least two policemen in Cairo and on April 2, a police general was killed when three bombs exploded in front of Cairo University.
More than 15,000 Islamists, mostly from Morsi's Muslim Brotherhood, have been jailed, while hundreds have been sentenced to death after what are often speedy trials.
The authorities blame the Brotherhood for the attacks and have blacklisted it as a "terrorist organisation".