A newly retired White Plains cop fatally shot his two teenage daughters and all three family dogs, then turned the gun on himself in the garage of their home Saturday, sources told The Post.

Glen Hochman, 52, who had retired only a few weeks ago, and his wife, Anamarie, had been having serious marital problems and, according to one source, had been talking divorce.

Police were called to the Harrison house at around 3:50 p.m. and found Hochman dead in the garage from a self-inflicted gunshot wound to his head. Hochman left a note at the scene, police sources said.

The slain daughters were Alissa, 17, a 12th-grader, and Deanna, 13, who was in the seventh grade. Found in their bedrooms, they’d been dead for hours, police said.

Anamarie, 50, and the couple’s eldest daughter, Samantha, had spent the day at the Mohegan Sun Casino in Connecticut.

Hochman was a 22-year veteran, said White Plains Police Public Safety Commissioner David Chong.

“The department is shocked and horrified by the news of this unfathomable tragedy,” Chong said in a statement. “We can only pray for the family.”

Just last May, Hochman won his department’s life-saving award for keeping an “unresponsive male’’ alive until paramedics arrived.

Described as mild-mannered and unassuming, he was also a longtime volunteer with Harrison Emergency Medical Services.

“Both were lost to incomprehensible tragedy,” Harrison School Superintendent Louis Wool said of the slain sisters.

“In this awful moment, let us remember how proud we are of them,” he said.

Alissa had worked at a local catering company, and recently practiced driving in the neighborhood, neighbor Howard Hollander told Lohud.

“I remember seeing him walking his dog,” one neighbor said of the family German shepherd. “He was just a quiet guy — I’m tearing up just thinking about this.”

“She was an absolutely adorable, sweet girl,” said Hollander, who also described the ex-cop as “always friendly.”

“They were both sweet girls,” the neighbor said.

A recent family photo showed Hochman sitting on a beige couch with the doomed daughters, their smiling faces framed by long brown hair. He had a small white dog cradled under one arm, and the German shepherd looked on watchfully. The third dog was not in the photograph.

Additional reporting by Leonica Valentine and Aaron Feis