The blast, which could be heard in several parts of the city, sent smoke rising above the Egyptian capital as a large number of ambulances rushed to the scene, the report said.
Health ministry spokesman Mohammed Fathallah told Egypt's private CBC network that at least two people were killed and 51 were wounded.
The explosion came on the eve of the anniversary of the start of the 2011 uprising that toppled Egypt's longtime autocratic ruler Hosni Mubarak.
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A Muslim Brotherhood-led coalition plans protests after Friday prayers across the country as part of their near-daily demonstrations against the July overthrow of Islamist president Mohammed Morsi and the recent vote on the country's rewritten constitution.
The state TV aired footage showing several wrecked and charred floors of the high-rise security building with the pavement outside littered with shuttered glass, pieces of bricks and rocks.
According to the report, gunfire resounded from the area immediately after the blast, but there were no other details.