Baghdad, Iraq ? A hidden bomb ripped through a tanker carrying chlorine gas Tuesday, killing nine people and filling hospital beds with more than 150 wheezing and frightened villagers after noxious plumes covered homes and schools north of Baghdad.

The attack was part of a string of blasts – including a suicide bomber who killed seven mourners at a funeral – that further rattled officials marking the first week of a major security crackdown seeking to calm the blood-soaked city. U.S. forces, meanwhile, called in airstrikes during intense clashes against insurgents in strongholds northwest of Baghdad.

With the death toll in the Baghdad area climbing above 100 since Sunday, Prime Minister Nouri al-Maliki tried to court some rare upbeat publicity with an even rarer event – leaving his heavily guarded quarters for a visit to the city’s streets and markets.

The fanfare of the security plan’s launch Feb. 14 has been swept aside by a steady roll of attacks, most blamed on Sunni extremists targeting the majority Shiites. Many Sunnis believe they are being sidelined by al-Maliki’s government and under growing threat from Shiite militias, which the prime minister refuses to confront.

Children stand amid debris in front of a car parts shop after a tanker truck exploded in Taji, some 12 miles north of Baghdad, Iraq. The tanker was carrying chlorine gas, and the blast killed one person and sickened more than 150 others.

The bombing of the tanker took place near Taji, 12 miles northwest of Baghdad. A military spokesman, Brig. Gen. Qassim Moussawi, said a bomb was planted under the tanker, but it was not known whether it had a timer or was remotely detonated. His remarks contradicted earlier reports that a roadside bomb blew up the truck.

Hospitals were soon flooded with terrified people – including many children – complaining of breathing problems, vomiting and stinging eyes. Most of the people treated were released after several hours and there was no apparent life-threatening cases, hospital officials said.

Chlorine gas in low exposure irritates the respiratory system, eyes and skin. Higher levels can lead to accumulation of fluid in the lungs and other symptoms, and death is possible with heavy exposure, according to the U.S. Centers for Disease Control and Prevention.

Authorities were left questioning whether the bombing could signal a new tactic by militants to try to spread greater panic with chemical fallout.