Iraq is under a high security alert following days of violence sparked by Wednesday’s bombing of one of the country’s holiest Shiite shrines in Samarra. At least 140 people, mostly Sunni Arabs, have been killed across the country. The Sunni-led Association of Muslim Scholars has said 184 Sunni mosques have since been damaged or destroyed. 10 clerics have been killed and 15 more abducted. The government imposed a rare daytime curfew today in Baghdad and in three other provinces — preventing many from attending Friday prayers. A series of joint Sunni-Shiite demonstrations have been held calling for national unity and to condemn the increasing violence. As many as 10,000 rallied in Basra alone. But many analysts fear Iraq is on the brink of civil war. The U.S. military is ordering its soldiers to stay in its barracks in Baghdad and to stay off the streets. On Thursday seven U.S. troops died. Meanwhile the staff of the satellite TV channel Al Arabiya is in mourning following the death of one of its best-known correspondents in Iraq. The 30-year-old Atwar Bahjat was assassinated along with her cameraman and soundman on Thursday.