Around 12:30 a.m. local time, a car hit multiple pedestrians near the East 9th Street and Red River Street, and East 10th Street and Red River Street intersections, the Austin Police Department tweeted.
Conflicting reports of how many people were injured emerged.
The Austin police tweeted that twenty-three people were taken to hospital — five of those critically injured. But Lt. Brian Moon told the Associated Press that 21 individuals were taken to hospital and among them five to seven had more serious injuries.
The driver of the vehicle has been taken into custody, police said.
The names of the deceased will not be released until next of kin have been notified.
In between East 9th and 10th streets on Red River Stree is the Mohawk, a bar where Tyler the Creator was performing for the SXSW festival.
SXSW runs from March 7 to 16, and is a celebration of music and film.