SPRINGFIELD, Mass. (AP) — A Massachusetts man fatally shot his downstairs neighbor, shot and injured two of her grandchildren, and then turned the gun on himself, authorities said.

The grandmother killed in Springfield earlier this week was identified Tuesday by Hampden District Attorney Anthony Gulluni as 52-year-old Kim Fairbanks.

Two girls, ages 10 and 12, suffered gunshot wounds. A 5-year-old boy was also in the home but not physically hurt. The three siblings were taken to a local hospital before the younger girl was flown to Boston Children’s Hospital in critical condition, Gulluni said.

“This is unequivocally one on the most heinous and cowardly acts to which I’ve had to bear witness as district attorney,” he said in a statement.

Police arrived at the multifamily home Monday afternoon after receiving reports of gunfire. Fairbanks was found dead alongside a dead dog in her first-floor apartment. The children were found in a bedroom.

Officers also found the suspected shooter, identified as 34-year-old Victor Nieves, dead of a self-inflicted gunshot.

Investigators say Nieves, who lived in the upstairs apartment, forcibly entered his neighbor’s front door and began shooting at the occupants before turning the gun on himself.

Authorities did not disclose a possible motive and the investigation is ongoing.