A suicide car bomber crashed his vehicle into a barrier outside a police building in central Iraq on Thursday morning, killing 20 police officers and wounding dozens more, a local councilman said.
The blast is the second significant attack in Iraq since the death of Osama bin Laden on Monday at the hands of a US commando team in Pakistan. Iraqis have been on edge, waiting for Al-Qaeda's branch in Iraq to strike back as a way to demonstrate it is still dangerous.
Iraqi officials have said they are increasing security in the wake of bin Laden's killing. Already security is vastly improved since the days when bin Laden's associates terrorised the country, but Thursday's deadly attack underscored how difficult it is for Iraq to wipe out all traces of the insurgency.
A police official said the bomber hit when officers were assembling in a square in front of the police building for a shift change in the city of Hillah, about 60 miles (95 kilometres) south of Baghdad.
A member of the region's Babil Provincial Council, Hamid al-Milli, said 20 policemen were killed and 40 more were wounded in the bombing. He said the car was believed to have been loaded with about 330 pounds (150 kilograms) of explosives. The attacker sped toward the police building and the guards did not have a chance to shoot at him, he said.
A witness at the scene said the blast knocked down the concrete ceiling covering a parking lot where many police cars were parked.
The fact that the bomber was able to wipe out so many policemen in one blast immediately raised questions about security at the building.
"The incident is definitely a security breach and all the security services in the province, especially the police command, are held responsible for that," said Mansour al-Mani'i, a member of the Hillah council.
AP television footage showed ambulances and police vehicles with blaring sirens racing to and from the blast sight. A bulldozer moved debris from the scene, where twisted metal, spots of blood and piles of bricks and rubble lay. Emergency teams lifted bricks and iron bars from the debris, while shards of glass littered the site.
The head of the Babil Provincial Council, Kadim Tuman, told reporters on the scene of the blast that he was holding both officials at the building and at the central government accountable.
"This building was not well fortified and the changing of policemen's shifts was exposed to the enemy," he said. The central government had also failed to provide extra police and explosive detection equipment.
The police building that was targeted is located in an important commercial area in Hillah. But many people were not yet at work, meaning the casualties were lower than they could have been.
Hillah is a predominantly Shiite city but its proximity to the Triangle of Death - a mainly Sunni area that at one time was one of the most dangerous in the country - has made it a frequent target of Sunni extremists.
There was no immediate claim of responsibility for Thursday's blast, but extremists like Al-Qaeda in Iraq have often tried to take out Iraqi forces as a way to undermine security in the country.
"The attack bears the hallmark of Al-Qaeda which is renewing its efforts to destabilise the country," said al-Milli.
At least four other people were killed in scattered violence around the country.
On Tuesday, a car bomb tore through a cafe in Baghdad packed with young men watching a football match on TV, killing at least 16 people.
Most of the dead and wounded in the cafe were young people. The blast occurred in a Shiite enclave in the former insurgent stronghold of Dora, an area in south-western Baghdad that saw some of the fiercest fighting of the Iraq conflict.
Nobody has claimed responsibility for that attack either, but Sunni insurgents have often targeted Shiites, who they don't consider to be true Muslims, as a way to incite sectarian violence.