A predawn shooting left one man dead, three men and a woman wounded, and bullet shells scattered on a sidewalk in downtown Denver, the latest eruption of gunfire that for years has plagued a LoDo area along Market and Larimer streets where nightclub party culture clashes with ritzy shops and pubs.

Police worked the scene all day but had no suspects Sunday night.

The killing, after a conflict escalated, piqued concerns that city leaders are failing to foster a healthy and safe environment. A fatal shooting last fall prompted police to roll in bright lights, limit parking and initiate installation of acoustic sensors to track gunshots and speed police response.

“The impression this gives is horrible,” said Carolyn Major, owner of the EVOO Marketplace and tasting room for olive oils and barrel-aged Italian balsamics, looking out at yellow tape and police cruisers flashing red and blue and crime scene investigators meticulously gathering evidence. She lost business Sunday with streets closed for more than 10 hours.

“Everyone wants Denver to stay good,” Major said. “But look what happens to this area after 10 p.m. How about more of a police presence then?”

Police responded to the shooting around 4:07 a.m. near the intersection of 15th and Market streets, just south of the 16th Street Mall, Lt. Matt Clark said. Investigators found two people had a conflict that escalated into a shooting, Clark said. But police still were trying to learn about the conflict and how many people fired shots and declined to discuss details.

One man died at the scene, Clark said, declining to name him. An ambulance carried two wounded men to the Denver Health Medical Center. Later Sunday morning, another wounded man walked into the hospital seeking treatment and was connected to the shooting. All were listed in stable condition.

A wounded woman also later sought treatment for non-life-threatening injuries at a hospital, police said.

Gang involvement is part of the investigation, police spokesman Doug Schepman said. “We’re still working to determine whether that was a factor in this incident.”

The shooting happened in front of a restaurant, near a hookah smoking establishment that closes at 4 a.m. A popular nightclub on Market Street, south of 15th Street, closed around 2 a.m.

Business managers and employees along Market Street echoed concerns that nightclub activity — starting Friday evening when the city’s public parking spaces are shut down or shifted to private valet parking — seemingly leads to violence out on streets late at night after closing.

Nightclubs provide internal security, including use of metal detectors to scan for guns and other weapons. A sign posted at one club prohibits “bad attitudes,” gang apparel and tattoos, ball caps, hoodies, oversize clothing and marijuana smoking.

South of 15th Street, Nallen’s Irish Pub manager Sean Nallen had gone home 15 minutes before the shooting and then received a phone call. On Sunday, when allowed back to his business, he counted at least 15 bullet shells near the intersection of 15th and Market.

Gunfire broke out in the area at least four times over the past two months, Nallen said, raising concerns about St. Patrick’s Day festivities if Denver residents are put off.

“We’re waiting for the city to take care of the business people who’ve been on this street for over 20 years,” he said. “They need to hold the nightclubs to a higher standard.”

Sunday’s killing followed a fatal shooting in September on Market Street that left one man dead and another in critical condition just before the 2 a.m. closing of bars.

Earlier that month, two men and a women were critically injured and carried to a hospital after a shooting in the 1500 block of Market Street.

At the end of 2018, city leaders decided to install extra lighting, using trailers and generators, and to limit parking on streets. Fixed cameras downtown already record people. Denver’s Shot Spotter acoustic sensors can pinpoint where gunfire happens, notifying police dispatchers and officers on patrol.

“We’re using these as a deterrent so that activity is more visible to both police and folks who are down there through that lighting and limiting parking on streets. … We definitely partner with everybody possible,” DPD’s Schepman said.

“We’re pushing, working toward starting the Shot Spotter as an additional tool so that we can respond as quickly as possible to gunfire — and try to identify individuals who are involved in incidents where guns are fired.”