ST. LOUIS – A Wells-Goodfellow grocery store reopened Monday, after a man was shot and killed there on Sunday.

Shoppers were back at the Schnucks on Union Boulevard, but they said the atmosphere inside felt subdued.

“It’s awfully quiet, people moving slow,” shopper Derel Plair said. “It’s usually fast pace, but it’s on everybody’s mind.”

St. Louis Metropolitan Police said the shooting happened around 3 p.m. Sunday when two men began fighting inside the store. One pulled out a gun and fired multiple shots, striking a 20-year-old man who later died at a hospital.

“Our officers were with small children inside the store and that was heartbreaking to see,” SLMPD spokesman Mitch McCoy said.

Outside the store, a car with apparent bullet holes was towed from the scene. Police believe the vehicle is connected to the shooting but did not go into details. Investigators said the violence appears to be an isolated incident.

Detectives are reviewing surveillance videos to determine how many people were involved and to identify the shooter. No arrests had been made as of Monday.

Late Monday afternoon, police released a photo of a person of interest connected to the investigation.

Anyone with knowledge on this person's identity or whereabouts, or with information of the shooting itself, is asked to call the city's Homicide Division. Tipsters who would like to remain anonymous and be eligible for a cash reward can contact CrimeStoppers at 866-371-TIPS. Only tips submitted to CrimeStoppers that lead to an arrest are eligible for the reward.