The victims were shot shortly before 11 p.m. Saturday during a Juneteenth celebration at Old Settlers Park in Round Rock, about 19 miles (30.5 kilometers) north of Austin.
An altercation began between two groups during a concert at the event, and someone started shooting, Round Rock Police Chief Allen Banks said during a news conference at the scene.
The two victims who were pronounced dead at the scene were not involved in the altercation, Allen said.
The shooting occurred near a vendor area away from the stage set up for the concert, Allen said.
Police officers and fire department personnel who were attending the event immediately began providing emergency medical care to multiple wounded victims, who were then transported to local hospitals, Allen said.
Police do not have a suspect in custody and investigators do not know how many shooters were involved. The investigation is ongoing, he said.
"It breaks your heart for a family that was coming out to enjoy their evening and now their life is forever changed as a result of somebody who could care less about somebody else's life," Allen said.