Kabul ? Gunmen with automatic weapons and suicide vests stormed a guest house used by U.N. staff in the heart of the Afghan capital early Wednesday, killing 10 people — including six U.N. staff — officials said. A Taliban spokesman claimed responsibility, saying it was meant as an assault on the upcoming presidential election.

Later, a rocket slammed into the grounds of the luxury Serena Hotel, which is favored by many foreigners. The device failed to explode but filled the lobby with smoke, forcing guests and employees to flee to the basement, according to an Afghan witness who asked that his name not be used for security reasons.

U.N. spokesman Adrian Edwards said six U.N. staff were killed and nine other U.N. employees were injured in the assault, which began about dawn in the Shar-e-Naw area of the city. Guests scurried from the building during the assault, and flames were seen on the roof as smoke billowed out and over the city.

Afghan police official Abdul Ghafar Sayedzada said 10 people in all were killed, including three attackers, and that police had taken control of the building. The bodies of three attackers were taken out of the house and sent for autopsy, said Gul Mohammad, an officer at the scene.

Edwards said officials were trying to account for several other U.N. workers who were staying at the guest house. He did not know their nationalities but said they were non-Afghans.

“This has clearly been a very serious incident for us,” Edwards said. “We’ve not had an incident like this in the past.”

A security guard, Noor Allah, said he saw a woman screaming for help in English from a second story window and watched as terrified guests leapt from windows. Afghan police using ladders rescued at least one wounded foreigner.

It was the third major attack on the capital in recent weeks.

On Oct. 8, a suicide car bomber detonated his vehicle outside the Indian Embassy, killing 17 people — mostly civilians — and wounding at least 76 more. The Afghan Foreign Ministry hinted at Pakistani involvement — a charge Pakistan denied.

On Sept. 17, a suicide car bomber killed six Italian soldiers and 10 Afghan civilians on one of Kabul’s main roadways.

Taliban spokesman Zabiullah Mujahid claimed responsibility for the attack on the guest house and the Serena in a telephone call to The Associated Press, saying three militants with suicide vests, grenades and machine guns carried out the assault.

He said three days ago the Taliban issued a statement threatening anyone working on the Nov. 7 runoff election between President Hamid Karzai and Abdullah Abdullah.

Afghans vote Nov. 7 in a second round election after U.N.-backed auditors threw out nearly a third of Karzai’s votes from the Aug. 20 ballot, determining widespread fraud. That pushed Karzai’s totals below the 50 percent threshold needed for a first round victory in the 36-candidate field.

President Barack Obama has been waiting for the ballot before deciding whether to send tens of thousands more troops to confront the growing Taliban insurgency. The fraud-marred election cast doubt on whether the Afghan government would be a reliable partner in the fight against the extremists.

The Kabul attack occurred one day after roadside bombs killed eight U.S. service members, driving the American death toll to a record level for the third time in four months.

The attacks Tuesday followed one of the deadliest days for the U.S. military operation in Afghanistan, with 11 soldiers killed in separate helicopter crashes.