A helicopter crash in Afghanistan killed 31 Americans, including as many as 25 Navy SEALs in one of the worst single-day losses of life since the war began, a senior military official told ABC News early this morning.

A total of 38 people were on board the Chinook helicopter when it crashed overnight in the eastern Afghan province of Wardak.

Initial reports indicate up to 25 Navy SEALs were on the aircraft at the time.

It was also carrying seven Afghan Special Forces troops, one interpreter, five member helicopter crew and one dog. . .