KABUL, Afghanistan — The Taliban delivered a dramatic response to President Hamid Karzai’s much vaunted peace overtures Monday with a coordinated series of attacks in the center of the Afghan capital.

According to Taliban spokesman Zabiullah Mojahed, 20 suicide bombers were loose in the capital. At about 9:30 a.m., they attacked several government buildings in and around Pashtunistan Square, including the Ministries of Justice, Finance, and Mines and Industries. Explosions also rocked the five-star Serena Hotel, the site of two previous attacks, and the Defense Ministry.

Reports claimed that insurgents had also attacked the presidential palace, where new cabinet members were being sworn in. The presidential spokesman denied that any breach had taken place, but the Arg, as it is called, was in the thick of the action.

For more than three hours, Kabul was almost completely closed down. Banks and stores were shuttered, and embassies barred their doors, not letting anyone in or out. Thick smoke blanketed the central portion of the city, and shots could be heard for blocks.

“I am fine, we’re all alive,” said a harried shopkeeper in Pashtunistan Square, answering his phone amid the chaos. “But I have to go now.”

The sound of firing could be heard in the background as he hastily hung up.

By noon the city was in a panic; more than a dozen explosions had been registered, and reports of dead and injured began to mount. Medical workers were just starting to pick up casualties when an ambulance packed with explosives detonated in front of a large shopping center, killing several police. After that the security forces began to ferry the wounded to hospitals in their own vehicles, no longer trusting the official ambulance fleet.

A little after 1 p.m. police announced that the remaining insurgents had been killed and the crisis had passed.

No information was immediately available on the numbers of dead or injured, nor could damage to property be assessed. One shopping center was burned out, and the Serena Hotel sustained some damage from grenade attacks.

Employees inside the hotel spent the day in a basement bunker, waiting for the all-clear. By early evening things were almost back to normal, according to a manager at the hotel’s spa.

“But there are no guests here. We are all alone,” she said.

The Serena has been the site of two previous attacks — one in January, 2008, in which insurgents stormed the building, killing at least eight, and another in October, 2009, when mortars fired into the courtyard exploded, shattering windows.

Monday’s attack is the largest in Kabul to date, and comes a little less than a year after a similar assault in February 2009.

The situation in the capital has been steadily deteriorating over the past 12 months; in October, an assault on a U.N. guesthouse left six dead and resulted in much of the U.N.’s staff being sent out of the country.

International organizations are now imposing more stringent rules on their employees, restricting their movements and ensuring that their living quarters are secure.

Afghans, meanwhile, shrug off the violence and go about their business.

“We have seen worse,” laughed a journalist from Wardak province, who had come to Kabul for a journalism workshop on Monday. “This is not so bad.”

This latest attack is likely to upset plans by the Afghan government to unveil a roadmap for reconciliation with the Taliban at the London conference, scheduled for January 28.

Karzai has made no secret of his wish to begin talks with the insurgents; he has publicly floated the idea of asking for Taliban leader Mullah Omar to be removed from the U.N. “black list” which restricts travel for those designated as terrorists, and freezes all of their foreign assets.

He has also complained repeatedly of the “mistakes” made in 2001 when the Taliban were excluded from the Bonn conference that outlined the structure for the new Afghanistan.

Karzai has called the Taliban “sons of the soil” and offered to embrace them as brothers if they agree to lay down their arms.

The United States has given qualified support to Karzai’s proposals, but Monday’s mayhem may well sour the mood.

The violence could not have come at a worse time for the Afghan president, who is fighting his own legislature in a bid to get a functioning government together ahead of the London conference.

Karzai’s first roster of nominees was soundly rejected; only seven out of 24 cabinet picks met with parliamentary approval. A second round of voting, held on January 16, gave him seven more. But he is running out of time, and the public rift has damaged his credibility with the international community.

The agenda for the conference had been worked out by the Afghan government; the major points were the fight against corruption and the opening to the Taliban.

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But with close to one-third of ministries lacking a confirmed head, Karzai will have a hard time convincing the international community that he is in a position to deliver on his commitments. And, as Monday’s violence showed, he is not in full control even of his own capital.

The attack may not have been a total surprise. Kabul residents say that security has been unusually tight around the capital for the past five days.

“There have been checkpoints at most intersections, with searches of every car,” said Roman Habib, a journalist in Kabul. “They were expecting something.”

For now, the situation is calm, and police insist that they have the situation under the control. Interior Ministry spokesman Zmarai Bashari went to so far as to tell the media that Monday’s attacks were a sign of the Taliban’s growing weakness.

But for those left in the dark and fearful capital, it will be an uneasy night.