Three people were killed and four others injured after an argument escalated into gunfire at an after-hours strip club in Detroit early Sunday, officials said.

Officers responding to reports of a shooting at 7:21 a.m. on a mostly residential street found three men suffering from fatal gunshot wounds, Detroit Police Chief Todd Bettison said during a news conference.

Four additional victims—two men and two women—were driven to area hospitals in private vehicles.

Bettison said all seven victims are believed to be in their 20s or 30s.

“A fight occurred, an altercation occurred, and as a result individuals decided to settle it with gun violence,” he said.

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The location has previously drawn police attention, Bettison said, noting that officers had responded to seven calls there this year. Investigators have leads, but he declined to provide additional details.

“This was an after-hours location,” Bettison said of the scene. “Imagine a strip club. … I’ll leave it at that.”

Detroit Mayor Mary Sheffield appealed to anyone with information to come forward and contact authorities.

“We know that we need more people to speak up to bring justice to the situation,” she said at the news conference. “It’s heartbreaking and our community should not suffer from this type of violence.”