An Interior Ministry spokesman says a suicide bombing has occurred but officials don't yet have any details. It wasn't immediately known if the bomb targeted a U.S. convoy.
Black smoke rose at the bomb site after the blast.
U.S. convoys often travel the road where the explosion occurred. The road leads to the U.S. base at Bagram.
U.S., NATO and Afghan security forces are on high alert this week because of the country's Presidential election on Thursday.
Kabul: Afghan officials say a bomb has exploded on the road leading from Kabul to the largest US base in the country.
First Published: Tuesday, August 18, 2009, 15:09