There are six victims in the incident, which happened around 11:30 p.m. at the corner of Broad and Ninth streets.
Deputies found a gun under a car parked on the 900 block of Broad Street.
Daniel Long, who was downtown for First Friday, said he heard four shots fired and then saw people scatter.
Capt. Scott Gay said there are people in custody, but did not say how many.
Gay said none of the injuries were life threatening.