Baghdad - A car bomb blast in the Iraqi city of Kufa, around 170 kilometres south of Baghdad, Tuesday killed 45 and wounded more than 80, police said.
The suicide attacker blew up his explosives-laden car in a market district near a school in the predominantly Shiite city.
Kufa is home to many loyalists of radical Shiite cleric Moqtada al-Sadr.
Seven schoolchildren were killed and three injured in attack on a school in Mandali in Diyala province.
A spokesman for health authorities told the Aswat al-Iraq news agency said their bodies had been taken to a local hospital.
Witnesses said a US military helicopter had opened fire on the school. The US military had yet to confirm the attack.
Also in Diyala province the Aswat al-Iraq news agency reported that a suicide attack on a police station Tuesday killed three policemen and wounded 11 people.
Earlier reports said gunmen had shot dead a married Iraqi couple Monday at an elementary school where both were teachers.
Independent news agency Voices of Iraq citing police sources reported that the pair were tied up and shot dead in front of pupils and colleagues in Khalis, north of Baghdad.
The killers made their escape following the attack.
Elsewhere, police in Baghdad discovered some 30 bodies of murder victims within a 24-hour period.
Four employees of Iraq's Higher Education Ministry were found dead Tuesday, Aswat al-Iraq quoted a ministry source as saying. The four, who were kidnapped Monday, were three ministerial bodyguards and a driver.
Analysts say the level of violence perpetrated by religious extremists and criminal gangs now is on the same level as that which plagued the city prior to the implementation of a new security plan three months ago.
Meanwhile US soldiers arrested 13 suspected al-Qaeda terrorists in Iraq, the military said Tuesday. One of those arrested is suspected of leading a Baghdad terror cell which prepared car bombs.
© 2007 dpa - Deutsche Presse-Agentur
Diyala province in Iraq. At least 7 school children are dead and 3 more injured after a United States military helicopter opened fire on a school in the Diyala province of Iraq. The helicopter was supposed to be firing upon militants located near the school.

"A U.S. helicopter shelled Al-Saada primary school, killing seven students and injuring three. The Mindli hospital received seven bodies and three wounded of a primary school's students," said an unnamed hospital official in Iraq. 

According to reports by Baghdad police, militants on the ground began to fire at the helicopter. The helicopter then returned fire, hitting the school in the process.

Lt. Col. Chris Garver, a spokesman for the U.S. military in Iraq said that an investigation was going to be conducted and that the incident is being taken seriously. Garver also said that the soldiers in the helicopter attempted to do whatever they could to avoid civilian deaths.