Video Shows Aftermath of Texas Mass Shooting, Chaos Inside Austin Bar

Here's what it looked like after a gunman opened fire inside a Texas bar over the weekend, killing three and injuring more than a dozen people ... some folks are hiding and some don't seem fazed.

TMZ obtained video from the aftermath of Saturday night's mass shooting at Buford's Backyard Beer Garden on Austin's West 6th Street ... and you see bar patrons cowering in fear, and hiding behind tables and columns.

At least a couple dudes were more interested in taking photos of themselves amid all the death and destruction than actually looking out for their safety ... you can see them boldly taking each other's photos in the middle of the room.

But, the vast majority of folks look like they're scared out of their minds ... and for good reason. A gunman had just shot up the place.

As we reported ... suspected shooter Ndiaga Diagne, was fatally shot by police officers minutes after he sprayed the bar with bullets from his own gun. The FBI is investigating the shooting as a possible act of terrorism.