Bad weather was a factor in the crash of a Black Hawk helicopter that crashed during a night-time mission in Afghanistan Thursday, officials say.

As many as four may have been killed in the crash that occurred in southwestern portion of that country.

U.S. Defense officials stated that four U.S. Troops were aboard the helicopter when it went down on its way to pick up troops from a combat outpost in the area. Officials say that they “don’t expect” that there were any survivors.

Officials say that weather played a role in the crash but haven’t ruled out enemy action as the cause.