Police in New Orleans say there have been 11 victims of a shooting incident near the French Quarter tourist hub.
Two people are in critical condition, with shots to the chest and torso respectively. No fatalities have been reported.
The incident took place on Canal St between Bourbon and Chartres streets at about 03:20 local time (09:20 GMT).
Police said on their Twitter feed that "one suspect had been apprehended near the scene".
They later said the person's possible involvement was still under investigation and that no arrests had yet been made. No other details have been given.
The victims have all been taken to hospital.
Video footage from the scene showed numerous police vehicles cordoning off the area as forensic teams made checks.
Local media quoted Police Superintendent Shaun Ferguson as saying officers on the 700 block of Canal Street at the time believed that they were being fired upon.
He said: "Unfortunately, there were so many people out here we were unable to determine who was actually firing shots at the time. We do not know how it started."
No police officers were hurt.
The French Quarter has been hosting holidaymakers marking the weekend after Thanksgiving.
Thousands of fans and alumni have also been drawn to the city for the Bayou Classic football game traditionally played on Thanksgiving weekend between Southern University and Grambling State University.