In the country's east, a suicide car bomber attacked a coalition base, killing two Afghan security guards, officials said, and the Taliban claimed responsibility for the attack.
A minibus ran over a roadside bomb in Obe district in the western Herat province, setting off a blast that killed at least 20 of the 25 passengers, said Raouf Ahmadi, a police spokesman for several provinces in western Afghanistan.
Abdul Bashir, an elder of a village in the district, put the death toll at 23. "It was a big, powerful blast," Bashir said. "Among the dead are men, women and children. The bodies are not easily recognizable."
Mohyuddin Noori, a spokesman for the province's governor, said the bus was on its way to a bazaar where the passengers were going to shop.
Noori also said that a small truck hit another roadside bomb today morning in the same district, seriously wounding at least four civilians.
The Taliban claimed responsibility for the suicide car bombing at a provincial reconstruction team base that Americans operate near Gardez, the capital of Paktia province.
There are more than 20 so-called PRTs across Afghanistan where international civilian and military workers train Afghan government officials and help with local development projects.
Abdul Ihay Atrafi, an Afghan Border Police commander for several provinces in southeast Afghanistan, said the bomber hid the explosives in a truck loaded with wood.