Neighbours say a mother’s scream alerted them to the heartbreaking scene inside a Toronto apartment building Monday, where a father and his six-year-old son were found dead in an apparent murder-suicide.

Toronto police say Zlatan Cico, 58, killed his six-year-old son, Simon Cico, before taking his own life at his apartment in Toronto’s east end, sometime around 7 p.m. on Monday. Investigators said the boy’s body showed signs of “trauma,” but further details have not been released pending a post-mortem analysis.

Next-door neighbour Pearse Vujcic and two others burst into Cico’s apartment on Monday, when they say they heard screaming.

“His wife was sitting on the floor screaming and yelling,” Vujcic told CTV Toronto. “The door was wide open and she was hoping that Simon, their son, was not inside.

“We went inside and we saw everything.”

Vujcic says Cico left a note, but would not comment on its contents. “They were good people,” he said of the family. “Good father. Good mother. Amazing child.”

Police say the mother is cooperating with their investigation.

Neighbours say Cico was separated from his wife and that the boy lived with her, but paid frequent visits to his father.

“For the rest of my life I am going to blame myself,” said Vujcic, who lived next door to Cico and considered him a friend. “He was down from time to time but… I didn’t notice that he was suicidal.”

With files from CTV Toronto