BAGHDAD -- Insurgents dragged five Shi'ite Muslim schoolteachers and their driver into a classroom, lined them against a wall, and gunned them down yesterday -- slayings in Iraq's notorious Triangle of Death that reflect the enflamed sectarian divisions ahead of a crucial constitutional referendum.
The shooting was a rare attack on a school amid Iraq's relentless violence, and it was particularly stunning because the gunmen targeted teachers in a school where the children were mainly Sunnis. Elsewhere yesterday, a suicide attack and roadside bombings killed 10 Iraqis and three Americans, bringing to at least 52 the number of people killed in the past two days.
The Iraqi and US governments have warned that Sunni Arab insurgents are likely to increase their attacks ahead of the Oct. 15 national referendum.
Shi'ite leaders have called on their followers to refrain from revenge attacks against Sunnis, fearing a civil war could result, though Sunnis have accused Shi'ite militias of carrying out some killings of Sunni figures.
But in one of the first public calls for individual Shi'ites to take action, a prominent Shi'ite cleric, Ayatollah Mohammed al-Yaaqubi, issued a religious edict yesterday allowing his followers to ''kill terrorists before they kill."
''Self-restraint does not mean surrender. . . . Protecting society from terrorists is a religious duty," Yaaqubi said. He also called on Shi'ites to ''deepen dialogue with Sunnis" who are not ''terrorists or Saddamists."
Earlier this month, Al Qaeda's leader in Iraq, Abu Musab al-Zarqawi, declared ''all-out war" on Shi'ites and vowed to kill anyone participating in the referendum.
Leaders of Iraq's Sunni minority are calling on their followers to vote against the constitution and defeat a charter they believe will fracture the country and seal the domination of the Shi'ite majority.
US and Iraqi officials tried to rally Sunni support for the referendum by releasing 500 detainees from Abu Ghraib prison outside Baghdad to mark the coming Islamic holy month of Ramadan, a step called for by Sunni leaders.
US defense officials in Washington said yesterday that a leading deputy to Zarqawi, identified as Abu Azzam, was killed this weekend. The officials spoke on condition of anonymity, citing the sensitivity of the information.
CBS News, quoting Pentagon officials, reported that US forces killed Azzam in a house raid in Baghdad on Sunday. CBS described Azzam as Zarqawi's top deputy, in control of financing foreign fighters coming into Iraq.
In the north, a top aide to Zarqawi surrendered to police in the city of Mosul, Iraqi Army Brigadier General Ali Attalah said. The aide, Abdul Rahman Hasan Shahin, was one of the most wanted figures in Mosul, Attalah said.
There have been few attacks on schools in Iraq, which have little protection, though children are constant witnesses to, and sometimes victims of, the violence.
Classes had just ended at the Al-Jazeera Elementary School in the village of Muelha, 30 miles south of Baghdad, when the shooting took place at about 1:15 p.m.
Police Captain Muthana Khaled said that as five Shi'ite teachers got into a minivan to head home, two cars pulled up carrying gunmen wearing police uniforms as a disguise.
The nine gunmen forced the teachers and their driver out of the van in front of students who were milling outside the school.
The attackers dragged the six men into an empty classroom, lined them against a wall and shot them to death, Khaled said. The gunmen escaped.
Farther south, gunmen yesterday assassinated a senior Shi'ite official from the Supreme Council of the Islamic Revolution in Iraq in the town of Qurna, near Basra, said Haytham al-Hussein, an aide to the leader of the party, one of the main factions in the government.
The gunmen kidnapped Azhar Qassem Abdul Wahid as he was leaving SCIRI headquarters, police Captain Mushtaq Kadhim said. Wahid's bullet-riddled body was found handcuffed and dumped by a roadside.
In other violence yesterday, a suicide car bomber in Baghdad attacked a police checkpoint guarding the oil ministry and several other government buildings, hitting a private bus carrying 24 ministry employees to work, said police Captain Nabil Abdel Qadir.
The blast killed at least seven policemen and three people on the bus and wounded 36 people, Qadir said
A roadside bombing in western Baghdad killed two American soldiers, and a third US soldier was killed in a bombing about 50 miles southeast of the capital, the military said. The deaths raised to 1,917 the number of US service members who have died since the Iraq war started in March 2003, according to an Associated Press count.