Baghdad (CNN) -- Car bombs rocked a number of predominantly Shiite Muslim neighborhoods of Baghdad on Monday, killing at least 13 people and wounding 53 others, police officials told CNN.
The violence adds to the particularly bloody fighting and political instability that Iraq and its capital, Baghdad, has seen in recent months.
Six car bombs detonated Monday in five neighborhoods across Baghdad within a period of about two hours, police said.
The blasts come two days after at least 19 people were killed in bombings in the capital. Separately, on Wednesday, at least 61 people were killed and scores wounded in attacks in Baghdad and across the country.
The United Nations said 2013 was the deadliest year in Iraq since 2008, with almost 8,000 people killed in violence, most of them civilians.
Fears of all-out sectarian war have increased since fighting broke out recently to the west of Baghdad in Anbar province, where al Qaeda-backed militants and Iraq's security forces have been battling for control of Falluja and Ramadi.
The violence recalls the bloody fighting at the height of the Iraq War that nearly tore the country apart.
On Saturday, U.S. Vice President Joe Biden talked with Iraqi Prime Minister Nuri al-Maliki about U.S. support for Iraq's fight against the Islamic State in Iraq and Syria, a group trying to overthrow the Iraqi government. Biden's office said the two leaders agreed on the importance of the Iraqi government's continued outreach to local and tribal leaders in Anbar province.