A coalition helicopter was shot down in eastern Afghanistan early Saturday morning, the NATO-led International Security Assistance Force (ISAF). Afghan government officials said 38 people were killed, including 31 American troops and seven Afghan soldiers.

CNN reported that 22 of those killed were members of the US Navy’s elite SEAL Team Six, the unit best known for assassinating Osama Bin Laden this past April, though sources say that none of those killed took part in that operation. The SEALs were being flown to a remote area for an operation to rescue other soldiers embroiled in a fierce firefight with insurgents.

ISAF confirmed a recovery operation is underway after one of its helicopters crashed in Wardak province, but gave no other details. “We are in the process of assessing the facts and will release more information as appropriate,” a spokesperson said. “Reporting indicates there was enemy activity in the area.”

If confirmed, the incident would be the deadliest since the NATO-led war began in late 2001. Other details were not immediately available.