Enemy fire forced down two US Chinook helicopters in southern Afghanistan on Sunday, the US military said on Monday.
The Chinook is regularly used as a troop carrier in Afghanistan
Five US and one Afghan soldier were injured when the helicopters made emergency landings at separate locations in the south.
A US military statement says both helicopters had been involved in combat operations against "enemy forces".
US-led coalition forces have come under mounting attack from Taleban and other insurgents in the south and the east.
The latest incidents bring to seven the number of US helicopters brought down by hostile fire or involved in accidents in Afghanistan this year.
In June, 16 US military personnel died when the Chinook they were travelling in was shot down by militants in the eastern Kunar province.
A sandstorm was blamed for a US helicopter crash in April that killed 18 soldiers - the single heaviest loss of life for US troops since they entered Afghanistan in 2001.
Five US soldiers were injured in one of Sunday's incident, north of Kandahar, when a Chinook made a hard landing, leaving the aircraft a write-off.
One Afghan soldier was hurt in the other, at a forward operating base south of Tarin Kowt in Uruzgan province when the helicopter returned to the base after coming under fire.
None of the injuries is serious, the US military statement said.
On Sunday, a man claiming to speak for the Taleban said its supporters had brought down the helicopter in Kandahar.
In a separate incident on Sunday, at least two people were killed in a suspected suicide bomb attack in the southern city of Kandahar, police said.
The suspected bomber was killed, as was a civilian. Two passers-by were hurt.
There were no reports of casualties among Canadian members of the US-led coalition who are thought to have been the target of the attack.
Suicide bombings in Afghanistan have risen this year, a number of them in the former Taleban stronghold of Kandahar.
More than 1,400 people have been killed in violence linked to militancy in Afghanistan this year, most of it in the south and east of the country.