Members of the SEAL Team Six were among the 31 U.S. special operation troops killed on Saturday when Taliban insurgents shot down a Chinook helicopter with a rocket-propelled grenade over eastern Afghanistan.

The SEAL Team Six is the special operations unit responsible for the Pakistan raid that resulted in the death of Osama Bin Laden. Saturday's death is being considered the deadliest day for American forces serving the decade-long war.

A person who was briefed on the casualties told Los Angeles Times that none of the elite unit's members on the raid against Bin Laden were on the helicopter that went down. That members of the team are dead just months after killing Bin Laden, who is said to be responsible for the attacks on September 11, is a major blow for the secretive team. It unknown how any of the 31 were SEALS, but it is believed to be dozens, according to the Los Angeles Times.

Fox News reported that President Barack Obama said their deaths are a reminder of the "extraordinary" price the U.S. military is paying in the decade-long Afghan war.

"We will draw inspiration from their lives, and continue the work of securing our country and standing up for the values that they embodied," Obama said, as reported by Fox News.

Seven Afghans were also killed and Obama said he also mourned their loss as they were people "who died alongside our troops in pursuit of a more peaceful and hopeful future for their country."

Defense Secretary Leon Panetta said he is deeply saddened by the loss, and that the U.S. will complete the mission to make the world a safer place.

The helicopter went down shortly after midnight Afghan time in the Sayedabad district of Wardak province, which is west of the capital, Kabul, Shahidullah Shahid, a spokesman for the provincial governor told the Los Angeles Times.

Shahid and other provincial officials told the paper that the crash came after a firefight that had left eight insurgents dead.

The NATO force has said recovery efforts were underway, and Afghan officials said the crash site had been cordoned off, according to the Los Angeles Times.

Afghan president Hamid Karzai has issued his condolences to Obama and the families of the Afghan troops who died, and identified the dead Americans as special operation forces, according to the Los Angeles Times.

The paper also reported that Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, warned against jumping to conclusions about the incident before investigators have completed their work. He added that the process of informing family members be respected, no matter how long it takes, and that people remember that "the troops we lose in this war aren't just statistics or numbers on a wall."