Egyptian police officer shot dead in Sinai CAIRO (Reuters) - A senior Egyptian police officer was shot dead by unknown gunmen who ambushed his car in the Sinai Peninsula town of El Arish on Saturday, security sources and state media said. Armed groups have exploited a security vacuum in the Sinai, which borders Israel, since a 2011 uprising ousted president Hosni Mubarak. The mainly Islamist and Bedouin groups have kidnapped tourists and police to press the government for the release of jailed colleagues. Three masked gunmen in a vehicle opened fire with automatic weapons on the officer, Brigadier General Mohamed Hani, as he returned from work on Saturday, state news agency MENA said. Hani's driver was seriously wounded, the report added. The motive for the shooting was not immediately clear. The interior minister ordered the formation of a team to comb the area and arrest the gunmen, MENA said, without naming any suspects. Over the past few days violence has broken out across Egypt between supporters and opponents of President Mohamed Mursi ahead of opposition rallies planned for Sunday to demand the Islamist president's resignation. At least three people were killed in protests on Friday, including a 21-year-old American student, and demonstrators have steeled themselves for more violence. Writing by Alexander Dziadosz; Additional reporting by Yusri Mohamed; Editing by Gareth Jones