Kabul, Afghanistan (CNN) -- A series of explosions rocked central Kabul early Monday, the day after Afghan security forces said they repulsed a wave of insurgent attacks in the capital and three other provinces.
The explosions persisted for some time, and followed periodic gunfire that lasted well into Sunday night in the Kabul district that houses government offices and allied embassies. There was no immediate explanation, but Afghan authorities had said late Sunday that they were trying to dislodge insurgents holed up in an empty building near the headquarters of NATO's International Security Assistance Force.
Interior Ministry spokesman Sediq Seddiqi said the remaining insurgents "have no choice except surrendering or to be killed by the Afghan forces."
"They came today with more than 20 insurgents and suicide bombers and attacked four provinces," Seddiqi told CNN Sunday. "As a result, they got nothing, and 19 of them were killed."
The assault was a rare occurrence in a heavily guarded part of Kabul -- but Gen. John Allen, the U.S. and NATO commander in Afghanistan, said the Afghans beat back the insurgents without allied assistance.
"They were on scene immediately, well-led and well-coordinated," Allen said. "They integrated their efforts, helped protect their fellow citizens and largely kept the insurgents contained." He said the attacks were meant to signal "that legitimate governance and Afghan sovereignty are in peril," but the Afghan response "is proof enough of that folly."
Seddiqi said two civilians were killed across the country, and 15 Afghan police officers were wounded. He said 15 of 19 suicide bombers were stopped before they could blow themselves up, with most of them killed by Afghan security forces.
And Lutfullah Mashal, a spokesman for the National Directorate of Security, said three men arrested in Kabul confessed to plotting to kill Karim Khalil, Afghanistan's second vice president. Two of the men planned to blow themselves up in Khalil's home, Mashal said.
The Taliban militia that once ruled most of Afghanistan claimed responsibility for the attacks, saying it launched fighters into battle with suicide vests, RPGs and hand grenades in Kabul and the provinces of Nangarhar, Paktia and Logar. But Mashal said the three men who targeted Khalil confessed to being members of the Haqqani network, a separate insurgent group that sometimes allies itself with the Taliban.
In his statement, Allen said, "No one is underestimating the seriousness of today's attacks." But ISAF spokesman Lt. Col. Jimmie Cummings described himself as "underwhelmed," and U.S. Ambassador Ryan Crocker told CNN, "The Taliban are very good at issuing statements, less good at fighting."
Crocker told CNN's "State of the Union" that no Americans had been hurt, but "our hearts go out" to the Afghans who had been killed or wounded. He suggested the attacks may be the work of the Haqqani network, rather than the Taliban, saying the Taliban did not have the capacity to carry them out.
NATO's International Security Assistance Force said as many as seven locations in Kabul were attacked, including Afghanistan's parliament building and the American, German and Russian embassies. Seddiqi said the insurgents took up positions in empty buildings in three Kabul districts to carry out the attacks, and still held one as midnight neared Sunday. Kabul police said they found and detonated a van full of explosives.
Meanwhile, an airbase used by U.S. troops in the eastern city of Jalalabad, in Naranghar province, also came under attack, the NATO command in Kabul reported. Four suicide bombers wearing women's burqas tried to attack the Jalalabad airfield where United States troops are based, airfield commander Jahangir Azimi said.
At least three of the attackers were killed, ISAF said in a statement about the incident.
Separately, a group of suicide bombers attacked the police training center in the city of Gardez, in nearby Paktia province. At least eight civilians were wounded, said a police official at the center, who is not authorized to speak to the media and asked not to be named.
And 15 would-be attackers were arrested in Kunduz province plotting similar strikes, said Lal Mohammad Ahmadzai, a spokesman for the chief of police for north and northeast Afghanistan.
The Taliban, the Islamist militia that once ruled most of Afghanistan, said the attacks were in retaliation for the killing of 17 Afghan civilians in Kandahar province last month. A U.S. Army staff sergeant, Robert Bales, has been charged with those killings.
But Jeff Dressler, an expert on the Haqqani network at the Washington-based Institute for the Study of War, told CNN that the coordination seen in the Kabul attacks indicate a Haqqani-led network was behind them, and that planned but disrupted attacks in the north may also be Haqqani-linked.
"This is likely their unofficial announcement marking the start of the spring fighting season," Dressler said. Though the attacks didn't succeed, he said, "The target selection was likely intended to send a message to the U.S., U.K., Russia and the Afghans that this will in fact be a bloody year for all forces in Afghanistan, particularly the east of the country."
U.S. Embassy spokesman Gavin Sundwall said he could not confirm that the embassy itself was the target of the attacks, but said gunfire had been heard in the vicinity. In a statement from London, Foreign Secretary William Hague said the British Embassy was one of the targets, but "every member of Embassy staff is safe."
"The Afghan National Security Forces responded to the attacks bravely, promptly and effectively, once again illustrating the significant progress that has been made in ensuring that Afghans can look after their own security," Hague said. The embassy premises sustained "limited damage," he said, and its staff "dealt with this dangerous situation extremely professionally."
India also said it had no reports of its nationals being wounded.
A local police official said attackers took over a central Kabul hotel close to the presidential palace, United Nations office and many foreign embassies, but both Seddiqi and staff at the hotel denied it had been attacked.
A western official in Kabul later said the hotel had been taken over by insurgents, but was then taken back by Afghan national security forces.
CNN's Masoud Popalzai, Fazal Ahad and Bharati Naik, Pentagon Correspondent Barbara Starr and Foreign Affairs Correspondent Jill Doughterty contributed to this report.