Afghanistan ? U.S.-led coalition forces using warplanes and artillery clashed with a small band of militants holed up in a house and a cave complex in eastern Afghanistan in fighting that killed seven Afghan civilians and wounded three, the military said Sunday.

The U.S. military launched an investigation into the deaths, inflicted during an operation involving 2,500 Afghan and coalition forces to counter an upsurge in attacks by Taliban-led militants.

The clash happened late Saturday in the Korangal Valley in the eastern Kunar province bordering Pakistan after American troops retaliated against an attack launched by eight to 10 militants firing small arms and rocket-propelled grenades, U.S. military spokesman Maj. Matt Hackathorn said.

U.S. soldiers on the ground called in warplanes and artillery to target militants sheltering in a house and nearby cave. Several militants were killed while the rest sought coverage in a compound housing civilians.

After the firefight ended, village elders told coalition forces that seven people had been killed and three wounded, Hackathorn said.