Baghdad (CNN) -- A series of explosions rocked Baghdad on Thursday morning, killing at least 31 people and leaving more than 50 others injured, Iraq's interior ministry said.
In a separate incident in Kirkuk, two car bombs exploded, killing four people and injuring 23 others, including six police officers.
The violence may continue a pattern of outbreaks following lulls.
March had the lowest monthly death toll since the U.S-led invasion in 2003, officials said earlier this month.
According to interior ministry figures, 112 people died violently in March: 78 civilians, 12 Iraqi soldiers and 22 police officers.
Until then, the lowest monthly death toll was in November 2009, when the country recorded 122 deaths.
Figures have fluctuated in Iraq month to month, with lulls in violence followed immediately by an uptick.
In March, Iraq hosted an Arab League summit, a gathering that signaled the political emergence of post-war democratic Iraq.
Security forces blanketed the capital in unprecedented security, and the gathering was a test of Iraq's ability to provide critical organization and security in the country where deadly violence remains a weekly norm.
Journalist Mohammed Lazim contributed to this report