A Chicago man with “anger management issues” shot and killed five of his neighbors at an apartment complex in the Dunning neighborhood on the city’s Northwest Side, on Saturday, Oct. 12, police said.

The shooting happened around 5:30 p.m. Saturday near the 6700-block of West Irving Park Road when Krysztof Marek, a 66-year-old retired construction worker, went into a second-floor unit and killed a family of three men and a woman as they ate dinner, ABC 7 Chicago reported.

He then went to the third floor and shot another woman, police said. The victim was taken to a hospital in critical condition where she was pronounced dead on Sunday, Oct. 13.

The two female victims in the shooting have been identified as Jolanta Topolska, 53, and Tsvetanka Kostadinova. The identities of the other three victims have not been released but all were adults, police said.

CPD First Deputy Superintendent Anthony Riccio said neighbors described the alleged gunman as having “anger management issues.” He said the man had a history of complaints from other residents but investigators “don’t know what set him off.” He has lived in the apartment building for about 15 years.

It was unclear how the man entered the apartments, but Chicago police said there was no forced entry. The suspect was known to the victims. He was taken into custody and a weapon was recovered at the scene.

Police announced that Marek has been charged with five counts of first degree murder and is scheduled to appear in bond court Monday.

Mayor Lori Lightfoot called the mass shooting “devastating and almost unfathomable” on Twitter on Saturday.

“We mourn the loss, honor the victims, and continue the hard but necessary work of keeping our neighborhoods safe, and taking guns out of the hands of those who are mentally infirm,” Lightfoot said.