An American airman was killed when a helicopter crashed due to technical problems in western Afghanistan, US military officials said.
The HH-60 helicopter came down in Herat province, close to the Iranian border, on Wednesday.
The helicopter was evacuating an Afghan election worker who had been accidentally shot by his escort.
Two injured US airmen and the Afghan national were taken to hospital at a US base outside Kandahar.
US military spokeswoman Lt Col Pam Keeton said the HH-60 was not brought down by hostile fire. One of the injured airmen was critically ill, she said.
The shot Afghan suffered no more injuries in the crash.
In a separate incident, a bomb attack injured three US soldiers and an Afghan in Paktika province, 175km (110 miles) south-east of the capital Kabul, on Wednesday.
Two Humvee vehicles were destroyed, a US military statement said.
Paktika Governor Gulab Mungal said Afghan forces had arrested a deputy of Taleban commander Jalaluddin Haqqani in connection with the attack.