Videos posted on Twitter showed people running through streets packed with restaurants and bars amid the sound of automatic gunfire.
The suspects were still at large and authorities said they had found a stolen handgun and were reviewing video footage posted to social media that showed what appeared to be an altercation before the gunfire erupted.
Detectives were trying to determine the sequence of events before the shooting and Sgt Eaton said they “don’t know if that fight actually lead to the shooting”.
Kelsey Schar, 18, was staying on the fourth floor of Citizen Hotel when she said she heard gunshots.
She walked to the window and “saw a guy running and just shooting,” Ms Schar told The Associated Press.
Numerous ambulances were dispatched to the scene and at least 12 people are now in hospital.
At least four of the wounded were hospitalised with life-threatening injuries. Authorities have not identified any of the victims or offered a possible motive.
Ms Lester said a police camera captured part of the shooting and investigators have located hundreds of pieces of evidence.
She described the scene as “really complex and complicated” – so much so that the bodies of the victims remained on the street hours later.
“We are asking for the public’s help in helping us to identify the suspects in this and provide any information they can to help us solve this,” she told reporters, urging residents to avoid the area.