A hidden bomb ripped through a tanker carrying chlorine gas 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. Tuesday's 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. US 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 Shi'ites. Many Sunnis believe they are being sidelined by al-Maliki's government and under growing threat from Shi'ite militias, which the prime minister refuses to confront.