A Brentwood man was electrocuted and died Sunday morning while trimming a tree in front of a Commack house, Suffolk police said.

Oscar Díaz, 39, a father of four and stepfather of three, was harnessed to a tree at about 10:30 a.m. on Roberta Lane when a safety line attached to him made contact with the uninsulated high-voltage line, said Suffolk County police Sgt. Jim Messina.

A medical examiner pronounced Díaz dead at the scene.

VideoMan electrocuted while trimming tree in Commack

Power lines weave through the trees on the street. PSEG Long Island spokesman Jeff Weir said nearly 100 customers temporarily lost power.

Díaz’s sister-in-law, Norma Velasquez, 36, of Brentwood, said the family had planned a Father’s Day barbecue in Díaz’s honor for Sunday afternoon. She said Díaz’s wife, Geydi Díaz, urged him not work on Sunday, but he said he needed to complete an unfinished trimming job.

Velasquez said Díaz typically worked seven days a week in the summer, often from “sunup to sundown,” because he had far less work in the winter and he wanted the best for his four children, his wife and his wife’s three kids, who lived with the couple.

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“He never complained about how hard he had to work,” she said. “He was always laughing, always telling jokes. I never saw him upset in the whole four years I knew him.”

Velasquez said her sister and Díaz married in August 2015 after about three years of dating. On Saturday night, the couple went out to dinner to celebrate Father’s Day. The two talked about how solid their relationship was, Velasquez said.

“My sister said, ‘I told him what made me fall in love with him. We were talking about all these wonderful things.’”

Oscar Díaz’s daughter, Jeimy Díaz, 17, said she loved watching her father and stepmother playfully run after each other.

“I had never seen him so happy” than since after he met his wife, she said.

Friends who worked with Díaz described him as an experienced tree trimmer. Díaz was working for G.A. Island Landscaping on Sunday.

Five days a week, Díaz worked for Santos Hernandez, owner of Hernandez Tree Trimming.

Hernandez said he was angry at the landscaping company.

“I would have never sent him up there without a bucket truck,” Hernandez said at the scene.

He said landscaping guys “know lawns. They don’t know trees.”

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The owner of G.A. Island Landscaping would not comment at the scene. He had been talking to homicide detectives.

Friends gathered on the street in Commack after the accident.

Rogelio Benitez, 29, of Brentwood,

said they all know the risks of tree trimming.

“Yes it’s dangerous. But we have to do it. We have our bills to pay and our families,” he said.

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Those at the house where Díaz died declined to comment.

Lorraine Michels who lives two doors down, said she woke Sunday morning to the sound of chain saws. Later her brother, who was outside, ran in, yelling, “He’s dead. He’s dead.”

PSEG is responsible for tree trimming and removal around power lines, Weir said. He said the utility should be called before any work is done around power lines. He said he did not know if anyone called the utility about the tree-trimming job.

— With David Olson