Four people have been killed after a car bomb exploded in busy shopping district of central Baghdad.br br Authorities say a number of people were injured in the blast.br br The area is inhabited by both Sunni and Shi’ite Muslims and is close to the Ishtar Sheraton Hotel, a famous landmark in the city.br br No group has claimed responsibility for the attack. br br Bombs in Baghdad are a common occurrence as heightened sectarian violence erodes Iraq’s social fabric.