The three car bombs and a roadside bomb hit three different areas of Baghdad -- two of them Shiite-majority, and another a mix of Sunnis and Shiites.
One of the car bombs exploded near an office of Al-Ahad television, which is affiliated with Asaib Ahl al-Haq, a militant group that split from powerful Shiite cleric Moqtada al-Sadr's Mahdi Army.
Violence in Iraq has increased markedly this year, with analysts saying the upsurge is driven by anger among the Sunni Arab minority that the Shiite-led government has failed to address, despite months of protests.