Ambulance at Walmart - Wonder What Happened??

As I was pulling into the Walmart parking lot, this evening, I noticed flashing lights on the far side of the parking lot.  It took me awhile to get across the parking lot as I was driving across the front of the store (all that pedestrian traffic).  The flashing lights that I saw were actually in the parking lot and not in front of the store.  As I got towards where the lights were coming from, a firetruck was pulling out (sans lights - as if leaving scene).  There was however an ambulance still there w/ it's lights still flashing and I saw an EMT in the back moving around.  I can only assume they were providing care for someone, but was unable to determine for sure as the only way to do so would be do walk up & peer in the back of the ambulance (which would look suspicious).