I doubt and still doubt the photos posted, the entire Adelanto police department responding to something in Apple Valley? Not on light on and neatly parked to a shots fired call?
As for the Muslims, plenty in the area. Would not surprise me if there was training going on.
Not sure why Adelanto cops were there. Perhaps an arrangement with the San Bernardino sheriff who must be spread pretty thin over their giant county.
However the camp ground was closer to Victorville which must have a much larger police force. Why didn't they respond?
UPDATE - there are no Victorville cops, they contract the sheriff.
When you say training I think Jamaat ul-Fuqra, the Pakistani non terror terror group with a number of camps in the US. There appears to be a camp in Oak Hill, CA, in the neighborhood.
Old thread Seeking Freepers for Jihadi Training Camp Observation and Information They'd have the sense to confine their firing to their land, and not likely at night