KABUL, Afghanistan — Seven suicide attackers killed at least 21 people in near-simultaneous assaults Thursday in a provincial capital in southern Afghanistan in the latest violent incident to shake President Hamid Karzai's government and its U.S.-led military allies.

The victims included 10 children and three women who died when an assailant crashed a vehicle into a hospital maternity ward and set off a cargo of explosives, officials said.

"The explosion was so powerful it rocked my house," Mohammad Daoud Zaheer, a retired district chief who lives a mile from the hospital, said in a telephone interview.

The Taliban claimed responsibility for the coordinated attacks, which seemed certain to keep Karzai and his U.S.-led allies off kilter and public anxiety running high amid a rash of high-profile assassinations and guerrilla-style strikes coinciding with the start of a drawdown of 33,000 U.S. troops from southern Afghanistan.

Afghan officials said that at least 38 people, including at least three police officers, were wounded in six hours of mayhem in Tarin Kot, the capital of Urozgan province, north of Kandahar.

The assailants targeted the governor's tightly guarded compound, where the provincial hospital is located, as well as the police headquarters and a private security firm. The security firm's owner, Matiullah Khan, a local power baron, escaped injury; his uncle, former Urozgan governor and Karzai aide Jan Mohammad Khan, was assassinated 10 days ago.

The provincial radio and television station was damaged by the vehicle bomb that hit the firm's compound, killing a reporter who also worked for the BBC World Service's Pashto-language service, officials said.

In calls to news agencies, a Taliban spokesman who claimed responsibility for the attacks expressed "regret" for the death of the radio reporter, Ahmad Omed Khpluwak.

Australian troops and helicopters from the U.S.-led International Security Assistance Force eventually intervened to end the fighting, said Mohibullah, the director of the provincial police anti-crime bureau, who like many Afghans uses only one name.

An ISAF spokesman, Capt. Pietro D'Angelo, confirmed that "ISAF supported the Afghan-led operation in Tarin Kot" and that ISAF helicopters evacuated injury victims, but offered no further details.

Zaheer, the resident, said, "If the foreign troops hadn't responded, the fighting would have lasted until tomorrow morning."

The attacks erupted at 1 p.m., officials said. According to an Afghan Interior Ministry statement, seven attackers wearing suicide vests struck several locations in Tarin Kot, while a motorcycle carrying explosives was detonated by remote control a few hundred yards away from the police headquarters.

At least 21 people and the assailants died, the ministry said.

Khan Agha Miakhel, the provincial public health director, said that the assaults began when one of the attackers crashed a vehicle through the gate of the governor's compound, slammed it into a wall of the maternity ward and set off its load of explosives.

Zaheer quoted residents living nearby as saying that two men firing weapons then stormed the compound, engaging in fierce exchanges with police for hours.

Around the same time, he said, a similar attack unfolded at the compound of the Highway Battalion, a private security firm owned by Matiullah Khan, the nephew of slain warlord Jan Mohammad Khan, the Karzai lieutenant killed in a July 17 assault on his home in Kabul, the capital.