CHICAGO (CBS) — Four people wounded early Wednesday in a shooting outside a Goose Island nightclub.

Police were called to Hearts Night Club at 1115 N. North Branch St. around 3:40 a.m., and when officers arrived, they found two men in their 30s who had been shot in the parking lot.

One victim had been shot in the leg and groin, the other had been shot in the chest and back. They were taken to Northwestern Memorial Hospital in critical condition.

Someone drove a third victim to Rush University Medical Center. That man was shot in the leg, and was being transferred to John H. Stroger Jr. Hospital of Cook County, due to the extent of his injuries.

A fourth victim was driven to Stroger with a gunshot wound to his arm.

A woman who saw the shooting said it stemmed from a dispute about one man blocking traffic while talking to a woman.

“After that, there was a fight. They broke the fight, and then the fight started back again down the lot, and then that’s where the gunshots started,” she said.

A former security guard at the club was among the victims. He was providing security for a private event at the upscale lounge. Police said the other three victims have long criminal records.

A woman who works for the club’s valet service said, “It’s just sad that a person that you see, that you have been working with, and you just see him as a security officer, that was working five months ago, that you see him just laying on the floor, and got shot.”

It wasn’t the first time violence has erupted on the grounds of Hearts. In April, a man was shot inside the club after a fight broke out in the hallway. That victim was listed in serious condition immediately after the shooting.