Baghdad, Iraq (CNN) -- At least 132 people were killed and 520 wounded in twin suicide car bombings in central Baghdad Sunday, officials said -- the deadliest attack on civilians in Iraq this year. Two car bombs detonated in quick succession near Iraqi government buildings about 10:30 a.m., an Interior Ministry official said.
One of the bombs exploded outside Baghdad's governorate building and the second one outside the Justice Ministry, about 500 meters (1,600 feet) away.
Plumes of smoke billowed from the sites of the attacks as victims fled, some with blood streaming down their faces. The streets were strewn with debris, including charred cars and chunks of concrete from damaged buildings. Some government buildings and others in the area were heavily damaged.
Sunday's attacks came a day after Susan Rice, the U.S. ambassador to the United Nations, completed a two-day visit to Iraq that included a stop at the nearby Foreign Ministry.
An Iraqi official said the government was working to bolster security, but regional cooperation was needed to help fight suicide bombers.
"We are calling on international and U.N. envoys to come and find out why Iraq is being targeted this way," said Ali al-Dabbagh, the Iraqi government spokesman.
The spokesman said Iraq's setbacks are mainly caused by a fledgling intelligence that has "not been completed."
The European Union condemned "this terrorist attack" and sent its condolences to the families of the victims, the Swedish presidency said in a statement.
The Foreign Ministry, near the site of Sunday's blasts, was one of six places attacked on August 19. That day's attacks killed at least 100 people and wounded hundreds more. The area is close to the heavily guarded Green Zone that also houses the U.S. Embassy.
The August attacks shook confidence in the abilities of Iraqi security forces who took over securing urban areas from U.S. troops over the summer.
The Iraqi government has blamed Syria for harboring former Baath party members, who it said planned the August attacks, and asked for their handover.
Relations between the two neighbors were strained after the bombings. Each withdrew its ambassador from the other's country.
Security in the capital was tightened after the August bombings, and a decision to normalize the situation in Baghdad by taking down blast walls was reversed and checkpoints increased.
Iraqi and U.S. officials have warned of a possible increase in violence ahead of the country's national elections scheduled for January 16.