It happened around 11 p.m. near 7th and South streets.
Investigators say a woman riding in an open-air "Slingshot" vehicle got into an argument with another woman working as a vendor at the festival.
They then engaged in a physical altercation.
Security officers were able to successfully break up the fight.
When the woman got back into the Slingshot vehicle the driver, a man wearing a mask and dark clothing, opened fire, striking one of the security officers two times.
The 40-year-old security officer was taken to the hospital and is listed in critical condition.
Police say the altercation stemmed from a group of dirt bikes, ATVs and open-air vehicle operators removing barricades that were in place for the event while workers were closing for the night.
Several bikes and ATVs were seen fleeing the scene.
No arrests have been made.