The United States "strongly" condemned Friday's bombings in Egypt and appealed for calm on the eve of the third anniversary of the Egyptian revolution.
"We strongly condemn the terrorist attacks that took place in Egypt today," the State Department said, urging that the bombings "be investigated fully and the perpetrators ... be brought to justice. We urge all Egyptians to exercise calm and restraint ahead of the third anniversary of Egypt's revolution."
A car bomb struck Cairo police headquarters on Friday, the first of four blasts targeting police, killing six people. (AFP)