At least 17 explosions in Iraq’s capital killed 65 people Thursday — the first major violence in the country since the United States completed its troop pullout last week.

In one attack, bombers painted a minibus to make it look like an ambulance, allowing them to get close to a government building before they detonated their explosives-packed vehicle, according to a spokesman for the Health Ministry. In another, a driver picked up a group of day laborers in a sport-utility vehicle before blowing it up. As people rushed to help, two more explosive charges went off, killing and injuring more people, witnesses said.

At least 207 people were injured in the attacks, as bombers also struck near a primary school and a vegetable market and appeared to target the convoy of a leading bank official.

Analysts said the apparently coordinated attacks bore the hallmark of well-trained insurgents, who took advantage of the U.S. pullout and the escalating political turmoil between Iraq’s Shiite and Sunni leaders. Mark Toner, a spokesman for the State Department, said the attacks were “linked clearly to this vulnerable period after U.S. forces have withdrawn” and when the Iraqi government “is finding its feet and moving forward.”

Sen. John McCain (R-Ariz.) said that “things are unraveling, tragically,” after what he has criticized as a premature withdrawal of U.S. forces. Interviewed on the CBS “Early Show,” he said: “We won the war, and we’re losing the peace.’’

Most of the attacks — 15 of them — erupted during a two-hour spree that began 6:30 a.m., said officials at the Interior Ministry, who spoke on the condition of anonymity because they were not authorized to make public statements.

No group asserted responsibility for the attacks, which were similar to previous ones carried out by the group al-Qaeda in Iraq. “From their perspective, it could not have been a better moment,” said Joost Hiltermann, deputy program director for the Middle East and North Africa at the International Crisis Group. “In times of political crisis, there are actors out there who want to push sectarian buttons. And I think that has happened.”

At least two more attacks erupted Thursday evening, including a car bomb that injured at least three civilians and explosive charges near houses and shops, according to government officials.

The violence comes just days after the end of U.S. combat operations in Iraq and — in the midst of a governmental emergency — threatens to rip apart the country’s fragile ruling coalition.

Prime Minister Nouri al-Maliki said the bombers will be punished. “I call upon all the religious men, the patriot powers and the tribes to support the security agencies in these very difficult circumstances,” he said in a statement.

But the bombings put him in a precarious spot. Hiltermann said most Baghdad residents just want to feel safe and receive basic services, such as electricity. In that context, he said, “they don’t really care who is running the country.”

The U.S. Embassy in Baghdad strongly condemned the attacks, saying, “It is especially important during this critical period that Iraq’s political leaders work to resolve differences peacefully, through dialogue, and in accordance with Iraq’s constitution and laws.”

On Monday, Maliki’s Shiite-controlled government shocked U.S. officials and other observers by announcing that an arrest warrant had been issued for Vice President Tariq al-Hashimi, a Sunni.

The warrant charges that Hashimi enlisted personal bodyguards to run a hit squad. The allegations threw Iraq’s political leadership into turmoil and sent Hashimi — who denies the charges — fleeing to the northern semiautonomous region of Kurdistan.

Maliki demanded Wednesday that Kurdish officials return Hashimi to Baghdad to face prosecution. The prime minister also threatened to purge his government of officials who refuse to work with him and to release incriminating information about officials unless they commit to ending violence and rebuilding Iraq.

Joel Rayburn, a military fellow at the National Defense University, said he is particularly concerned about heavily Sunni provinces that want to break off from the central government. Rayburn said that Maliki’s government wouldn’t let that happen and that it could lead to more violence, noting that this was his personal opinion and not that of the university’s.

Iskander Witwit, the deputy head of the parliament’s security and defense committee, said the explosions Thursday were in many ways expected because of the political turmoil. “The insurgents, of course, are taking advantage of this,” he said.

“What had happened today was intended to give Iraqi people an idea that the security forces aren’t able to handle security simultaneously with the U.S. withdrawal from the country,” Witwit said in an interview.

He said Iraqi security forces need to beef up nighttime operations and set up more surprise checkpoints, in addition to the permanent checkpoints established throughout Baghdad. “Everybody has been aware that the terrorists are using the nights to practice their activities and plant explosive charges,” Witwit said.

The wave of attacks included at least four explosive-laden cars, two operated by suicide drivers. Police were able to defuse or safely detonate an additional five such cars, officials said. Also, a Katyusha rocket was fired into a western Baghdad neighborhood, killing one person and injuring another.

Qassim Atta, a spokesman for the Baghdad Operations Command, told the government-run Iraqiya television station that the explosions targeted civilians randomly, not specific establishments.

Babil province, about 80 miles south of the capital, imposed a curfew after receiving intelligence that explosives-laden cars had entered the area, according to an Iraqiya report.

Special correspondent Asaad Majeed in Iraq and staff writer Karen DeYoung in Washington contributed to this report.