Two car bombs exploded in a main square of central Baghdad on Tuesday morning, killing at least 57 people and wounding 148, police said. Gunfire sounded immediately after the blast and thick black smoke could be seen rising from the site. It was not immediately clear who was shooting" police or insurgents continuing the attack. The suicide car bomber appeared to drive into one of the crowds of labourers who waited for work and detonated an explosives vest as the nearby-parked car bomb also went off. The square is located near several government ministries and a bridge that crosses the Tigris River to the heavily fortified Green Zone, where Iraq's parliament and the U.S. and British embassies are located.