Six policemen have been injured as a large bomb went off near a national security building in Cairo, Egyptian officials said.
The car bombing tore the facade off of the government building in the Shubra residential neighbourhood and was felt across the Egyptian capital.
It demolished a wall in front of the government building and smashed its structure, leaving gaping holes exposing its offices.
The area was flooded with water from broken pipes and vehicles were wrecked. Glass from blown-out windows could be seen on the streets for blocks around the site of the blast.
The explosion took place amid a wave of attacks and killings this summer, including the assassination of Egypt's attorney general by a car bomb in Cairo.
A new anti-terrorism law was finalised this month.
The legislation sets up special courts and protects its enforcers in the face of a two-year-long Islamist insurgency that aims to topple President Abdel Fattah al Sisi's government.
Human rights groups have criticised the law and accused the government of rolling back freedoms won in the 2011 uprising that toppled autocrat Hosni Mubarak.
