Suicide bomber kills four in Cairo, two more blasts follow

MILITANT ATTACKS ON THE RISE

But authorities are struggling to contain Islamist militant violence. Militants based in the Sinai have stepped up attacks on security forces since Morsi's fall, killing hundreds, and Egypt's political transition has stumbled.

Attacks in other parts of Egypt have also risen, fuelling fears the country could face an Islamist insurgency similar to one that raged in the 1990s before Mubarak stamped it out.

The Sinai-based Islamist militant group Ansar Bayt al-Maqdis said in December it was behind a car bomb attack on a Nile Delta police compound that killed 16 people and wounded about 140.

On Thursday, gunmen killed five policemen at a checkpoint south of Cairo, the Interior Ministry said.

Prime Minister Hazem el-Beblawi condemned the Cairo Security Directorate attack in a statement, saying it was an attempt by "terrorist forces" to derail the political road map which was nevertheless being implemented "firmly".

The police headquarters assault will likely encourage the state to crack down harder on the Brotherhood, which it accuses of terrorist acts. The group says it is a peaceful movement.

Human rights groups accuse security forces of widespread human rights abuses in their crackdown on the Brotherhood. But the group has little sympathy on the street.

The mood was tense at the site of Friday's suicide bombing. "Traitors and dogs!" yelled onlookers, an apparent reference to the assailants.

People also chanted anti-Brotherhood slogans. "The people want the execution of the Brotherhood. Execution for Morsi," they yelled.

Wafaa Ahmed cried outside the Cairo Security Directorate.

"These people have no sense of loyalty to the nation. This is terrorism, they want to get back at us because we finished them off ...," she said. "Something like this will only make the people stronger and more determined."