Cairo - Four Egyptian policemen were wounded in a bomb attack on a bridge in the capital on Friday, the Interior Ministry said.
The attack shattered a tense calm in Cairo after a spate of bombings on January 24 killed six policemen, in an escalation of a militant campaign following the overthrow of Islamist president Mohamed Morsi in July.
The Interior Ministry said two small bombs went off near policemen stationed on a bridge near central Cairo, the official said.
It was not immediately clear whether the devices had been planted there or were thrown by assailants.
Live television footage showed police vehicles and ambulances at the scene of the attack.
Militant attacks on policemen and soldiers have killed scores, mostly in the restive Sinai Peninsula, since Morsi's overthrow by the military on July 3.
Sinai-based jihadists have also claimed responsibility for attacks targeting police in Cairo and elsewhere.
An al-Qaeda-inspired group based in the Sinai said it carried out a car bombing outside Cairo police headquarters on January 24 that killed four people.
Two more policemen were killed in three additional bombings in the capital that day.