A Chicago man with apparent “anger management issues” killed five neighbors in an apartment complex shooting over the weekend, police said.

Krysztof Marek, 66, was "identified as the individual who fired a handgun multiple times striking five victims" at about 5:35 p.m. on Saturday in the 6700 block of West Irving Place, Chicago police said in a statement on Monday.

The victims included two men, one of them 61 years old and the other between 40 and 45. The three women killed were 65, 53 and one between 30 and 35.

The 53-year-old slain woman was identified Jolanta Topolska, the Office of the Medical Examiner of Cook County told NBC Chicago. Another victim was Tsvetanka Kostadinova, whose age was not known, the station reported.

The gunman entered a neighbor’s apartment on the city's northwest side where three men and a woman were eating dinner and fatally shot them, Chicago police Deputy Superintendent Anthony Riccio said.

Marek, a retired construction worker, then went to another apartment and fatally shot a fifth person, officials said. He is custody and not cooperating with investigators, Riccio said.

The shooting “definitely wasn’t random,” Riccio said, according to NBC Chicago. The gunman had lived in the building for 15 years and knew his victims, he said.

“We don’t know what set him off tonight," Riccio said, according to the station. "Most of the occupants inside the building have had problems with him in the past, but certainly nothing of this magnitude."

Ricccio added that neighbors told authorities the man had "anger management issues."