US President Barack Obama offered condolences on Saturday to the families of 31 US soldiers killed in a helicopter crash in Afghanistan.
"My thoughts and prayers go out to the families and loved ones of the Americans who were lost earlier today in Afghanistan," Obama said in a statement.
"Their deaths are a reminder of the extraordinary sacrifices made by the men and women of our military and their families, including all who have served in Afghanistan."
The president also paid tribute to seven Afghans who died in the crash, Xinhua reported.
US defence secretary Leon Panetta said he was "deeply saddened" by the loss of American troops and their Afghan counterparts in the incident.
"We will stay the course to complete that mission, for which they and all who have served and lost their lives in Afghanistan have made the ultimate sacrifice," the secretary said in a statement.
Earlier on Saturday, Afghan President Hamid Karzai released news of the crash, which happened in the country's east.
While military officials are continuing to investigate the cause of the crash, Afghan media reported Taliban had claimed responsibility, saying a helicopter was shot down by militants, leaving several people aboard dead.
The helicopter crashed in Wardak province during a military operation Friday night, Karzai's office said in a statement.