A motorcyclist wearing what may have been an explosives vest hit NATO and Afghan security forces in Khost, killing three members of the NATO-led security force and an Afghan interpreter, the U.S. Embassy in Kabul and President Hamid Karzai's office said, CNN reported.
A Western source told CNN the three security force dead were U.S. soldiers.
An additional 17 civilians were killed and 32 injured, the report said.
Four children and two women were among eight killed in Logar province when a vehicle hit a roadside bomb planted by the Taliban, a Twitter message from the Interior Ministry said, CNN reported.
Karzai's office and the embassy issued statements condemning the attack. The embassy called it "cowardly."
In Kunar province, authorities said at least 21 militants were killed after a NATO air raid, Khaama Press reported.
A spokesman for the provincial governor said air support was called after coalition forces fought with militants at the Wata Pur and Mangoi districts in Kunar province.
The spokesman said no Afghan security forces or civilians were killed.