A U.S. Chinook CH-47 helicopter was shot down by insurgents in eastern Afghanistan killing 30 American service members and seven Afghan commandos in what is the the deadliest single day loss for coalition troops in the war in Afghanistan.

The helicopter crashed around 3:00 am Saturday in Wardak province. A spokesman for the Taliban said it fired a rocket at the helicopter as it was taking off following a battle in which coalition forces had killed eight militants in a raid on their hideout. U.S. officials said it appeared the aircraft was shot down. The NATO alliance said it was investigating the cause of the crash.

U.S. officials said 25 of the Americans on board were special forces, including 22 Navy SEALs believed to be from the elite SEAL Team 6, the same SEAL unit that killed al-Qaida leader Osama bin Laden in a raid in Pakistan last May. However, none of those on board the helicopter were involved in the bin Laden raid.

“Their deaths are a reminder of the extraordinary sacrifices made by the men and women of our military and their families,” Obama said in a statement Saturday. “We will draw inspiration from their lives, and continue the work of securing our country and standing up for the values that they embodied.”

Marine Gen. James N. Mattis, commander of U.S. Central Command, said: “We grieve for our lost comrades and especially for their families, yet we also remember that the lads were doing what they wanted to be doing and they knew what they were about. This loss will only make the rest of us more determined, something that may be difficult for those who aren’t in the military to understand.”

It was the deadliest attack on the U.S. military in Afghanistan since June 2005, when insurgents shot down a U.S. helicopter during Operation Redwings in the eastern province of Kunar, killing 16 American troops.