The attack outside the Ittihadiya palace, where newly elected President Abdel-Fattah el-Sissi holds office, raised alarm among officials today over the security breach.
Militants were able to carry out the attack despite multiple closed-circuit security cameras in the area and warnings from the militant group that it planted bombs at the palace.
Egyptian militants have carried out scores of attacks, mainly targeting security forces, in retaliation for the fierce crackdown on Islamists since el-Sissi then the army chief ousted President Mohammed Morsi almost exactly one year ago. The government says 250 policemen have been killed since August last year in targeted attacks.
In a strongly worded statement, a coalition led by Morsi's Muslim Brotherhood called for mass street protests on the one-year anniversary of his ouster on Thursday, warning it will be a day of "monumental anger," and urging its supporters to rally in 35 mosques in Cairo ahead of street rallies.
More From This Section
The group, which refuses to recognise the new government, denies the charges, and it and its allies accuse the government of staging the attacks to lay the blame on Morsi supporters.
Ajnad Misr, or Soldiers of Egypt, which has claimed previous attacks on police, said it carried out yesterday's bombing at the palace in a statement that evening. It said it set a trap for guards at the Ittihadiya palace using new explosive devices that cannot be detected by ordinary equipment.
It said targeting the Ittihadiya palace was to "show that the less important government headquarters and personnel are much easier to reach.