A powerful blast tore through a police headquarters in an Egyptian
Nile Delta city early Tuesday, killing 13 people, wounding more than 100 and leaving victims buried under rubble in the deadliest bombing yet in a months-long wave of violence blamed on Islamic militants.
Investigators were trying to determine whether the blast, soon after midnight in the city of Mansoura, was from a car bomb or from explosives planted around the building.
The explosion left a downtown street of the city strewn with piles of debris and charred cars.
