As the encore of Sound Tribe Sector 9 took flight early Sunday morning this past weekend, rocks at a Denver area amphitheatre fell onto unsuspecting members of the crowd.  Though no deaths have been reported, seven people were injured, four of which required hospitalization.

Occurring 1 a.m. Sunday morning, a loud bang erupted through the encore performance at the Red Rocks Park and  Amphitheatre originating at the northern end by a formation called Creation Rock.  Described by concert attendees as sounding like an explosion, rocks suddenly fell from Creation Rock onto the stairway below striking several people.

The massive formation is one of two 300-foot natural rock structures within the amphitheatre in Morrison, Colo. just over 12 miles southwest of Denver.

However, the venue has not witnessed an incident such as this in over two decades.  Though city officials have already brought out private investigators to determine how the rocks became loose enough to fall; local area news outlets have reported that attendees of the STS9 show saw people climbing the rocks, despite acute warning signs against climbing the rock faces and substantial fees for violating that warning.

Without a doubt, I can confirm that I saw two (people wearing) T-shirts, climbing on the edge of Creation Rock, Jeremy Hewett told ABC 7’s local Denver affiliate, the Denver Channel.

If his account is correct, those two people if identified will face a minimum $999 fine with the possibility of jail time.

Of those whom required hospitalization, 34-year-old Jennifer Ackerman suffered severe head injuries; she has been in the Intensive Care Unit at Saint Anthony’s Hospital since Sunday.

Though she is conscious and in fair condition, Ackerman’s injuries include fractures to her skull, a sizable gash on her head, and some cracked teeth.  She is expected to be discharged from the ICU later this week.

Loose debris from the rock slide has since been removed by Police from the Creation Rock area and by all authorized estimation, the venue is still safe to attend.  Local authorities along with private parties are currently investigating the rock fall.