STATEWIDE - Police across the region are reviewing their security plans for several major outdoor events this month.
This weekend and next, Austin will host the Austin City Limits Music Festival at Zilker Park. An estimated 75,000 people are expected each weekend. Right after that, Circuit of The Americas will be home to the U.S. Grand Prix.
San Antonio wraps up the month with the Mala Luna Music Festival in the parking lot of Nelson Wolff Stadium.
Both police departments say they're analyzing the potential for attacks from nearby high rises.
"At this time there are no threats that have been made against ACL," Austin Interim Police Chief Brian Manley said.
"I think it's important to understand that law enforcement or intelligence agencies aren't going to stop every attack," said Fred Burton, chief security officer of Stratfor Enterprises.
Burton is also a former counterterrorism agent for the U.S. State Department. He said the threat is very real.
"This is almost your worst-case scenario," he said. "It's also a potential textbook, I'm afraid, for organizations like Islamic State, al-Qaida and al-Qaida on the Arabian Peninsula to think about."
San Antonio Police Chief William McManus said the biggest threat is a lone attacker who does not discuss plans prior to carrying them out.
"This is not preventable unless we have intelligence that would lead us to believe that something like this would happen - any information at all," McManus said.
He said anyone who finds themselves under attack should "get small."
"Get real small and run for the exit, if you can," he said.