DENVER -- The owner of Chopsticks and Sushi Restaurant has been arrested, accused of shooting and killing a male customer inside his busy eatery Thursday afternoon.

Yan De Yang, 40, was booked on investigation of first-degree murder, police spokeswoman Loretta Beauvais said Friday. Detectives will present their case file to the Denver District Attorney in the next several days.

Police said there are no other suspects involved in the deadly shooting, which occurred about 3:30 p.m. at the Welton Street restaurant, a half-block off the 16th Street Mall.

Beauvais would not say what sparked the violence, other than that there was a physical confrontation between two groups of people inside the restaurant. The investigation is ongoing.

Police are working to confirm the identity of victim, who died at Denver Health Medical Center. He had been shot "multiple times," police said. The coroner's office scheduled an autopsy on the victim to determine the cause and manner of death.

A witness told 7NEWS that Yang was briefly placed in handcuffs soon after the shooting and taken in a police car for questioning.

"I heard two loud gunshots around 3:15 p.m. It was very loud," said Peggy Irvin, who owns Body Massage Wellness Spa, just two doors down from the restaurant.

She said when she ran out, she saw people stumbling out of the restaurant in a daze.

"I saw a girl crying and so I just asked if everything was OK and she said someone had been shot in the restaurant," Irvin said.

Irvin said police officers asked her and her spa clients if they'd seen anyone running from the restaurant. She hadn't. Irvin asked police what caused the shooting, but officers said it was hard to get details because of language barriers with the eatery's Asian staff.