Santiago said multiple people were being questioned Monday, but no arrests had been made and police are still searching for other possible suspects.
“Our detectives are trying to narrow down the scope of how many shooters we are dealing with," Santiago said, adding that detectives were still collecting shell casings outside the restaurant.
The dead included a 17-year-old boy and his 29-year-old brother, as well as a 21-year-old man, Santiago said. Police have not released their names.
The wounded included a 16-year-old boy who was critically injured and required surgery overnight, but Santiago said he was expected to survive.
In a statement Monday, the restaurant said it was cooperating with the police investigation while trying to make sense of a “heartbreaking event.”
“Our hearts go out to the victims, their families, and all affected by this senseless violence,” the statement said.
Social media videos shared by the restaurant earlier Sunday before the shooting showed people dancing near a stage with a DJ booth.
Santiago said event organizers removed a group of people from the venue after they started fighting near the stage. They began shooting at each other just outside of the event, Santiago said.
Bystander Lupe Rodriguez said he ran to safety when he heard the gunshots. He was shaken, but said he was grateful that he and his friends survived.
"There was a man on the ground, and it didn’t look like he made it,” Rodriguez said. “His father was yelling out his name.”