The AH-64 Apache gunship crashed on Friday while conducting exercises on a helicopter firing range near the main American base at Bagram, north of the capital of Kabul, the US military said in a statement.
Hostile fire was not suspected in the incident, it said.
The aircraft's two crew members were taken to the US base for treatment and are in a stable condition, said US army spokesman Lieutenant-Colonel Jerry O'Hara.
"It was a training accident on a live fire range," he said. "The crew members were recovered and both of them are still at the medical facility on base getting taken care of. They're going to be fine."
The cause of the accident, which happened at night, was not immediately known, but US forces have secured the crash site and are conducting an investigation.
The crash comes a day after the US military said a US-led coalition Chinook helicopter had been destroyed by a blaze that broke out as it made a "hard landing" with six crew and 25 Afghan soldiers on board. No one was hurt.
The massive, twin-rotor helicopter had been taking troops to fight militants near Spin Boldak, a town close to the border with Pakistan.
Last month, a Chinook that had been modified for special forces operations was shot down in eastern Kunar province, also near the border with Pakistan, killing all 16 US forces on board.
A memorial for the US soldiers
killed in a Chinook crash
In April, 15 US service members and three American civilians were killed when their Chinook went down in a sandstorm while returning to the main US base at Bagram.
In a statement on Thursday, the military released the findings of an investigation into the cause of the April crash. It said "the aircraft encountered a severe dust storm with winds over 45 knots that caused the pilots to lose outside visibility."