CAIRO — Violence erupted across Egypt on Friday as tens of thousands of demonstrators filled Tahrir Square to mark the second anniversary of the country’s revolution with an outpouring of rage against the rise to power of the Muslim Brotherhood. At least seven protesters and two police officers were killed in clashes in Suez, the state news media said.

More than 250 people were injured in similar battles around government buildings across the country, including the Interior Ministry, the presidential palace and the state television building in the capital. The deaths reported in Suez took place near the provincial government headquarters, which protesters set on fire.

The Egyptian military deployed armored vehicles in Suez on Saturday to restore security, several news organizations reported. On Friday, Muslim Brotherhood offices were ransacked or burned in at least three cities, including Ismailia, the Suez Canal town where the group was founded 85 years ago.

In the most striking episode, masked men attacked the offices of the Brotherhood’s Web site in Cairo, upending furniture, littering the floor with broken glass and papers and smashing computers. Several witnesses said the assailants came in a large group to the third floor, carrying pellet guns and acid to burn through the padlock, and left with computer hard drives.