According to The City of San Antonio: 

"The City of San Antonio has closed Alamo Plaza to vehicular and pedestrian traffic every night beginning 8:30 p.m. June 2, 2020 through 6 a.m. Sunday, June 7, 2020. The closure is a precautionary measure to minimize the possibility of civil disturbance and damage to sensitive structures."
 
"The City will reassess later this week to determine if any closures beyond the weekend are necessary. The San Antonio Police Department will increase staffing in the downtown area to mitigate any potential disturbances."

 You can read the full message here: https://www.sanantonio.gov/gpa/News/ArtMID/24373/ArticleID/19002/City-of-San-Antonio-announces-temporary-closure-of-Alamo-Plaza