Authorities on Thursday identified the gunman and his five victims in the Wednesday shooting at Molson Coors’ headquarters in Milwaukee, with the city’s police chief calling it an “unspeakable tragedy.”

Milwaukee Police Chief Alfonso Morales identified the shooter as Anthony Ferrill, a 51-year-old electrician for the brewing company, but gave no details on his possible motive.

“Right now there’s an investigation going on. I think it’s premature to speculate on anything,” Milwaukee Mayor Tom Barrett said Thursday. “I think this is the time again, be there to grieve and support the families.”

The five victims in the Wednesday shooting were identified as Jesus Valle Jr, 33; Gennady Levshetz, 51; Trevor Wetselaar. 33; Dana Walk, 57; and Dale Hudson, 50. “All of the victims and the suspect worked at Molson Coors. No members of the general public were involved in this incident,” Morales said.

The Milwaukee Fire Department and Milwaukee police responded to the shooting at around 2 p.m., and several schools and businesses in the area were placed on lockdown.

According to the Milwaukee Journal Sentinel, Ferrill and several co-workers were in the midst of a long-running dispute when the electrician returned to the headquarters with two guns and began to opened fire.

Ferrill, who had worked as an electrician at Molson Coors for 17 years, then turned the gun on himself. One co-worker told the newspaper Ferrill believed he was being racially discriminated against and frequently argued with at least one of his victims, a fellow electrician.

The co-worker added that Ferrill would often watch movies on his phone during his shift—which other electricians did not condone. About a year ago, Ferrill’s behavior changed, the colleague said, and he started saying he believed his fellow brewery workers were coming into his home and bugging his computer.

“I was, ‘Are you serious, Anthony? What?’ We all kind of joked about it, saying we should maybe get him an aluminum hat. Things just started getting weird. But he was dead serious about it,” the co-worker told the Milwaukee Journal Sentinel.

The sprawling complex where the shooting occurred includes several corporate offices and brewing facilities where at least 600 people are employed. The area, known as “Miller Valley” in reference to the Miller Brewing Co., also features a 160-year-old brewery.

Molson Coors, which owns the Coors and Miller beer brands, officially changed its name from MillerCoors in 2019.

“We’re all a family here at Molson Coors in Milwaukee, and this is an unthinkable tragedy for us,” Gavin Hattersley, president and CEO of Molson Coors, said in a statement obtained by The Daily Beast.