BAGHDAD — As Iraqis flooded the streets of their capital and other cities on Saturday to celebrate Id al-Fitr, the holiday that marks the end of the holy month of Ramadan, a string of car bombs struck in mostly Shiite neighborhoods, killing more than 60 people, officials said.

The bombings were the latest in a surge of attacks in Iraq this summer — before, during and after Ramadan — that have brought monthly death tolls to levels not seen in nearly five years, according to United Nations figures.

The attacks on Saturday killed at least 61 people and wounded more than 200 across Iraq, an Interior Ministry official said.