Five powerful car bombs rocked Baghdad on Tuesday, killing 112 people, including women and students, and wounding 207 in the third co-ordinated massacre to devastate the capital since August. The attacks shattered a month of calm in the city and come as the war-torn country's leaders prepare to announce the date for a general election early next year, the second since the US-led ouster of dictator Saddam Hussein. Three car bombs exploded near offices of the labour, interior and finance ministries and a suicide attacker in a car struck a police patrol in Dora, in southern Baghdad, causing 15 deaths, an interior ministry official said. The first explosion in the centre of Baghdad was heard at 10:25 am (1225 PST), another came within seconds and a third one minute later. Although no group has yet admitted responsibility, the timing of the blasts and the fact that three of them targeted government buildings bears all the hallmarks of an Al-Qaeda operation. Sporadic gunfire erupted after the explosions, followed by the sound of sirens from emergency vehicles as helicopters took to the skies and roads were cordoned off, causing gridlock across the city.