Fire Department spokesman James Garrett told The Kansas City Star Anthony Bruno, a six-year veteran of the department, was fatally shot about 2:30 a.m.
City police said the officer who shot him was in uniform but working another job off-duty. The officer, whose name hadn't been released, had responded to a reported assault on a cab driver at 12th and Wyandotte streets and encountered a suspect near 13th Street and Baltimore Avenue. Police said the man started to attack the officer as the officer approached, the newspaper said.
The officer, who told investigators he feared for his life, shot Bruno in the chest, the newspaper said.
Bruno, a third-generation member of the fire department, died later at a hospital.
The officer was hospitalized with serious injuries.
Fire Chief Paul Berardi said in a statement that "specific details of the incident are still being gathered."
"Friends and family of the Kansas City Fire Department remember Anthony Bruno as a courageous and dedicated firefighter who had been with the department since 2008," the chief said.