A CNN report with some more details and more questions:
Officials said the 12 man Green Beret-led team had just completed a meeting with local leaders and were walking back to their unarmored pick-up trucks when the unexpected ambush resulted in a firefight that lasted 30 minutes.
(Later) .....the unit in Niger "had actually done 29 patrols without contact over the previous six months," Joint Staff Director Lt. Gen. Kenneth F. McKenzie Jr. told reporters.
Link:http://edition.cnn.com/2017/10/13/po...nce/index.html

The film clip has a sentence akin to Niger has not given the USA permission to launch air strikes.