Police fire gas over Cairo's Tahrir Square CAIRO (AP) - Volleys of tear gas left a white cloud over Cairo's Tahrir Square and surrounding streets in the vicinity of Egypt's Interior Ministry, in the fourth day of clashes between security forces and rock-throwing youth protesting a deadly soccer riot. Black-clad riot police fired rubber bullets from armored vehicles on Sunday to push protesters away from the ministry, while building walls of concrete on street entrances. Since Thursday, 12 people have been killed in Cairo and Suez, a hotbed of anti-government protests to the east of the capital. Egypt entered a new cycle of violence following riots Wednesday in the Suez Canal city of Port Said that left 74 dead. Protesters accuse the security forces of deliberately failing to prevent the bloodshed. EL-ARISH, Egypt (AP) - An Egyptian security official says attackers have set off explosives along a gas pipeline in the country's Sinai peninsula, halting exports to neighboring Israel and Jordan. The blast that took place Sunday at dawn is the twelfth successful attack on the line since the popular uprising that ousted longtime Egyptians leader Hosni Mubarak in February last year. The official says the attack by presumed Islamist militants caused huge fires, but fire engines put it out hours later. He spoke on condition of anonymity because he was not authorized to speak to the press. The mountainous peninsula has seen a surge in lawlessness in the last week. On Friday two Americans were briefly abducted by Bedouin tribesmen in the latest of a series of kidnappings.