Saturday became the deadliest day for American forces in the war in Afghanistan after insurgent shot down a Chinook transport helicopter, killing 30 Americans.  Some of the Navy Seal commandos from Seal Team 6, the unit that took down Osama bin Laden, were among those killed.  Eight Afghans were killed, said American and Afghan officials. 

The helicopter was on a night-raid mission in the Tangi Valley of Wardak Province and was apparently brought down by a rocket-fueled grenade, a coalition official told the New York Times. 

President Obama gave sympathy to the families of the Americans and Afghans who died in the attack. "Their death is a reminder of the extraordinary sacrifice made by the men and women of our military and their families," President Obama said in a statement.  "We will draw inspiration from their lives, and continue the work of securing our country and standing up for the values that they embodied," he added.  President Hamid Karzai of Afghanistan also offered condolences.

Saturday's attack was consistent with a recent surge in violence that accompanies goes hand in hand with a drawdown of American and NATO troops.

The Taliban claimed responsibility for the attack.