Story highlights The comprehensive review of the timeline has been ordered by US Africa Command

The preliminary findings are expected to be established at the end of the week, but they are expected to remain classified

(CNN) The Defense Department is conducting an initial review of the mission in Niger and the ambush by 50 ISIS-affiliated fighters that left four US soldiers dead and two wounded.

Multiple US officials have described to CNN a scene of confusion on the ground during the unexpected firefight. The investigation will be an effort "to get all the facts correct," an administration official familiar with the review told CNN.

The review will aim to determine precisely what happened -- something that is still not clear nearly two weeks after the incident occurred, according to the official.

The comprehensive investigation of the timeline has been ordered by US Africa Command and includes all the military branches and elements of US intelligence agencies that were involved in the mission. Team members who were on the ground are being interviewed about what happened as well as preparations for the mission.

The preliminary findings are expected to be established at the end of the week, the official said. But they are likely to remain classified and be used to determine several other matters, including: whether a formal military investigation is warranted, whether military procedures and intelligence analysis need to be changed to avoid future incidents, and how Congress will be briefed on the ISIS ambush that resulted in the deaths of four soldiers.

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