The soldiers were killed late Thursday near Asadabad, the capital of mountainous Kunar province bordering Pakistan, Master Sergeant Cindy Beam told
She confirmed that the wounded marine was in a stable condition but said no other details would be released until next of kin had been notified.
The last two months have seen more than 10 members of the US-led coalition of 20,000 marines, soldiers, air personnel and special operations and intelligence forces killed in Afghanistan.
Six died in May and another two in June, one killed by a roadside bomb in south central Afghanistan and the other during a "non-hostile" incident at the main US base at Bagram north of Kabul that is still under investigation.
More than 2,000 US marines are deployed to Afghanistan, and are engaged in offensives against suspected Taliban and Al-Qaeda militants mainly in the south, south central and southeastern regions.
The rugged areas surrounding Asadabad, are believed to be infiltrated by members of the ousted fundamentalist Taliban regime as well as militants loyal to wanted warlord Gulbuddin Hekmatyar.
Kunar police commander Matiullah Safi said American-led military activity had taken place near Asadabad on Thursday.
"We don't know if any American has died but on Thursday American helicopters were flying over and around Asadabad and they bombed a hilltop some seven to eight kilometres north of the American base," which is in the west of Asadabad town, he said.
The latest deaths bring to 131 the number of US-led coalition troops killed in Afghanistan since an American-led offensive began in late 2001 to oust the Taliban regime following the September 11 attacks against the United States.
The number of attacks against Afghan and coalition troops has increased in recent weeks, while some 80 suspected militants have been killed in the southeast in American-led offensives.
The offensives have been designed to flush out militants in the known "Taliban heartland", the neighbouring provinces of southcentral Uruzgan, southern Kandahar and southeastern Zabul, ahead of landmark Afghan presidential and parliamentary elections planned for September.
Remnants of the Taliban have threatened to disrupt the polls.