BAGHDAD, Iraq (UPDATE)-- At least 112 people were killed in central Baghdad and more than 400 were wounded early Tuesday when suicide bombers exploded their cars in a series of five terrorist attacks, Iraqi authorities said.

The attacks shattered a two-month period of relative calm in the capital that had existed since twin car bombings killed and wounded hundreds of people in late October.

Tuesday's attacks left at least 112 people dead and at least 425 wounded, the Interior Ministry said. Among the dead were children and students, said Brig. Gen. Qassim Atta, a spokesman for the Baghdad Operations Command.

The first of the vehicles blew up in southern Baghdad's Dora district at about 10 a.m. (0700 GMT), followed by four more car bombs about half an hour later.

Three of the bombings struck at the heart of the Iraqi capital, detonating a few minutes apart. One hit the Ministry of Labor and Social Affairs and another hit the new site of the Ministry of Finance near al-Qashla Square; the ministry's former building was destroyed in a bombing in August.

Another bomb exploded in the busy commercial district of Nahdha, and the fifth bomb blew up outside the Karkh Civil Court in western Baghdad's Mansour district.

Suicide bombers carried out the five attacks, Atta told CNN.

The sounds of sporadic gunfire and emergency sirens could be heard immediately following the attacks. Smoke from the blasts was seen billowing into the morning sky.

Suicide bombers were also responsible for the two bombings October 25 in Baghdad, which killed 160 people and wounded 540.

The bombs detonated in quick succession at mid-morning on a Sunday, the first day of the workweek in Iraq, in the Salhiya district of central Baghdad. The location was close to the Foreign Ministry.

Government officials including Baghdad's governor questioned how the bombers were able to penetrate the area's security, which was supposed to have been improved in the months leading up to the attacks.

Authorities subsequently detained more than 60 people responsible for security in the district where the bombings took place.

Meanwhile on Tuesday, Iraq finally set a date to elect a new parliament, the head of the country's independent electoral commission said.

"After intensive discussion with the presidential council we've all agreed on March 6, 2010 to be the new date for the parliamentary elections," Faraj al-Haidari told CNN. The country's president and two vice-presidents have approved the date, he said.

There has been intense wrangling in parliament over the passage of an election law, and one of the country's vice-presidents vetoed earlier versions of the legislation, pushing back a vote that had been planned for January.

CNN's Mohammed Tawfeeq contributed to this report.