A powerful blast rocked near a state security headquarters in Egyptian capital Cairo early Thursday amid reports of casualties.
A car-bomb went off outside a National Security building in the northern Cairo suburb of Shubra al-Kheima, the Interior Ministry said in a statement.
At least six policemen were injured in the blast, which caused damage to the building, the ministry said.
A medical source said that more than 20 people were injured in the explosion.
According to eyewitnesses, a number of nearby buildings were damaged in the blast.
There has been no claim of responsibility for the bombing.
Egypt has been roiled by violence and turmoil since the military unseated democratically-elected President Mohamed Morsi in 2013.
Thursday's blast came two days after President Abdel-Fattah al-Sisi issued a tough anti-terrorism law, which sets the death penalty for some terror offenses.