Ten people were killed on Monday in a bombing of the security headquarters of Egypt’s South Sinai province and an ambush of soldiers near the Suez Canal city of Ismailiya, security officials said. Five people died in the car bombing, which occurred as senior officials were holding a meeting, the officials said.

At least 50 people were reported injured in the blast in al-Tor, the provincial capital.

The security building and the adjoining provincial governor’s office were damaged in the blast as staff fled in panic, the officials said. Officials said the bomb was thought to have been concealed in a previously stolen police car.

Five soldiers were killed west of the Suez Canal when gunmen opened fire on their patrol, security officials said. Another soldier was hospitalized in serious condition. No immediate claims of responsibility for either attack had been made.

Security forces have come under attack west of the Suez Canal, and Islamist extremist groups have intensified their activity in the Sinai Peninsula to its east since the military’s ouster of democratically elected Islamist president Mohamed Morsy in July.

The latest attacks came a day after 53 people were killed as security forces and civilian supporters dispersed marches by Morsy loyalists in Cairo and other cities.

More than 400 people were also reported to have been arrested in the clashes while tens of thousands of supporters of the military-backed interim government celebrated the 40th anniversary of the 1973 Arab-Israeli war in Tahrir Square.

The Islamist National Alliance in Support of Legitimacy called for demonstrators to head to Tahrir again next Friday, calling it “the property of all Egyptians.”

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