John D'Atri says he was delivering a housewarming gift to Karen Skellas when her estranged husband, Loannis, screamed something at her in Greek and then shot her in the head Sunday, The New York Daily News reports.
While D'Atri rushed to call 911, the husband reloaded his double-barreled shotgun and killed himself.
"From out of nowhere this person appears with a hood over his head," says D'Atri. "In the blink of an eye, he came towards her and fired.
Police say the murder-suicide happened just days after the couple separated. Karen Skellas had moved to her daughter's Gravesend apartment.
Skellas was a medical records worker at Lutheran Medical Center.
Her husband owned a construction business.