The Taleban militia claimed the Kabul bombing, which a spokesman from President Hamid Karzai's office said killed two US nationals, two Afghans and three Nepalis in front of the offices of an international security company.
Taleban spokesman Abdul Latif Hakimi said the bomb was detonated by a Taleban fighter using a remote control device.
"A few minutes ago he phoned our chief ... to say that he finished his mission and is alive," Hakimi said.
The Taleban was ousted from power by a US-led alliance in late 2001 and is now waging a campaign of violence to disrupt Afghanistan's first presidential elections on October 9.
The blast in the upscale Shar-i-Naw area of Kabul, where dozens of aid agencies are also located, injured an unspecified number of other people and destroyed several vehicles, an Afghan official said.
Afghan police cordoned off the site of the explosion as ambulances rushed to the area to transfer injured people, witnesses said.
SCHOOL BLAST KILLS 9 CHILDREN: At least nine children and one adult were killed in a separate blast, which ripped through a school in Paktia province on Saturday night, a US military spokeswoman said.
"There were four children, five teenagers and one adult killed," Master Sergeant Ann Bennett said from the US military press centre in Kabul.
Bennett said an eight-year-old boy injured in the school explosion was being treated at a US military base, but she was unsure how many more wounded there were.
"The explosion took place last night inside a private madrassah," Paktia Governor Haji Assadullah Wafa told Reuters by satellite phone.
The school was in the village of Naiknaam, near the town of Zormat, 125km south of Kabul, according to the Pakistan-based Afghan Islamic Press agency.
The premises were also used by a non-government organisation for teaching Afghan women.
Paktia's governor said there were contradictory reports about the cause of the blast, with some saying it was an explosive device placed on a motorcycle parked outside the school and others saying a device was planted inside the school.