The shootings were reported to Tequila KC Police at 1.27 am, according to spokesman Thomas Tomasic.
The four policemen found four dead at the bar.
Five others were transported to hospitals in the area, all in stable condition, Tomasic said.
The victims were not identified. The suspect has not yet been identified, police said.
“We don’t have a good description yet to identify a suspect or suspects, we don’t know how many were there,” Tomasic said.
Investigators are now investigating surveillance video cameras in the area. Police have evacuated the bar and are awaiting a search warrant.