- ISIS said the bomb was retribution for the execution of six men in May
- Egyptian authorities said the executed men had connections to terrorist in Sinai who regularly attack police and military
The car detonated near the National Security Building in the northern suburb of Shubra al-Kheemag, Egypt's Health Ministry said. The driver had parked it then was picked up by a motorcycle and fled before the explosives went off.
Among the 29 wounded were six police officers, the Interior Ministry said.
The blast echoed through the capital for miles, waking residents in predawn hours, London Times reporter Bel Trew told CNN.
Video revealed at least one building facade nearly defaced, cars mangled, and heavy concrete street barriers knocked over near the bomb site.
ISIS claimed responsibility for the attack in a statement posted on Twitter. The group said it was carried out to avenge the execution of six defendants in the Arab Sharkas case in May 2015.
Human Rights Watch reported that the six men were part of a group of nine convicted in attacks on security forces and killing two armed forces officers in a shootout in 2014.
Egyptian authorities said the men were connected to the Islamist militant group Anbar Beit al-Maqdis, which has sworn allegiance to ISIS, according to Egyptian state media.
The group is based in the Sinai, where it has carried out multiple attacks on police and military.
In recent months, militants have increasingly launched brazen and deadly attacks. The frequency of the attacks picked up after Egypt
's army overthrew President Mohamed Morsy -- a former Muslim Brotherhood leader -- following a popular uprising in July 2013.
Earlier this week, President Abdel Fattah el-Sisi signed a tough counter terrorism law that gives Egyptian authorities sweeping surveillance and detention powers.