But Baghdad residents expressed outrage at the government's inability to keep peace in the city.

The twin bombings in what was supposed to be one of the city's safest areas came as Iraq prepares for pivotal elections in January that are to determine who will guide the country through the U.S. withdrawal.

The blasts seemed designed to undermine Prime Minister Nouri al-Maliki, who has staked his political future on restoring safety.

"Al-Maliki always appears on TV bragging that the situation is stable and security is restored. Let him come and see this mass destruction," said Ahmed Mahmoud, who returned to a blast site yesterday to search for his brother's head after identifying his headless body at a morgue from the belt he was wearing.

"I took the body to Najaf for burial," he said. "Then I came back looking for the head."

U.S. and Iraqi forces searched for the leader of a vehicle bomb-making network believed to be connected to the attacks, raiding buildings in Baghdad yesterday, the U.S. military said.

There have been no claims of responsibility, but massive car bombs have been the hallmark of Sunni insurgents seeking to overthrow the country's Shiite-dominated government.

"This explosion made people more furious. People will not reelect this government," said Ahmed Hassan, 50, a Ministry of Education employee, who said he was now terrified to go to his job.

Senior leaders, including the prime minister, president, and parliament speaker, renewed flagging efforts to work out an election law acceptable to all factions and help the country move forward with the January vote, an official close to the talks said.

American and other observers worry that failure to agree on the guidelines might delay the vote and potentially slow down the planned U.S. withdrawal.

There were few details on the latest proposal, which the official said would be presented to party leaders today before going to the parliament. The official spoke on condition of anonymity, citing the sensitivity of the talks.

Iraqi authorities tightened hundreds of checkpoints that already dot the city, snarling traffic for hours. Security reinforcements flooded into the streets, after authorities said they had intelligence showing other targets were next.

Three major government buildings were destroyed or severely damaged in Sunday's blasts, all within a few hundred yards of one another. The first blast hit the Justice Ministry and the Ministry of Municipalities and Public Works across the street. The second struck the Baghdad Provincial Administration, akin to City Hall.

A busload of children leaving a day-care center next to the Justice Ministry was caught in the first blast and 24 children and the bus driver were killed, hospital and police officials said. Six children were wounded, the officials said, speaking on condition of anonymity.

The two vehicles - a minivan and a 26-seat bus, each packed with thousands of pounds of explosives - likely had to pass through multiple security checkpoints before reaching their targets, Maj. Gen. Qassim al-Moussawi said.

"These attacks are targeting the symbols of Iraqi sovereignty, and they aim to paralyze the government," said Foreign Minister Hoshyar Zebari, whose ministry was targeted in a similar bombing in August.

Sunday's attacks came as the government continued to reel from the Aug. 19 bombings, which also targeted the Finance Ministry. Those attacks caused delays in paying government workers this summer and hindered reconstruction projects because paperwork was lost.

The structural damage at the Justice Ministry appeared severe yesterday. The ministry oversees the country's chronically crowded prisons and is in the process of deciding which inmates in U.S. custody it wants to keep as the Americans continue to reduce their detainee population.