Addendum: my own dad sent me the following in an email.
“I was 12 years old and growing up in Austin when the Tower Sniper attacked. My brother and I went up on the roof of our house to see what was going on. We couldn’t hear the shots but we could see white puffs when bullets struck the granite.”
There was not a big police presence on the ground that day, and Whitman himself was not shooting the facade of the tower. What my dad and uncle saw was probably mostly civilian gunfire.