A Coram father serving his fourth and final military tour was among six American service members killed this week by a suicide bomber near Bagram Air Field in Afghanistan, his family said Tuesday.

Louis Michael Bonacasa, 31, a staff sergeant with the New York Air National Guard 105th Base Defense Squadron, had previously served in Iraq, Qatar and Saudi Arabia.

He was four months away from returning home, where he and his wife planned to have a second child and buy a home, the family said.

“He said this was going to be his last tour, and he was going to retire in a couple years,” said a sister, Raquel Bonacasa, 27, of Edgewater, New Jersey.

Bonacasa is the first Long Island military casualty in Afghanistan or Iraq in three years, records show. The oldest of four siblings, he leaves a wife of 11 years, Deborah, and a 5-year-old daughter, Lily.

Vincent Bonacasa, 28, of Selden, said his brother was “a humble man” devoted to family who “took a lot of pride in what he did.”

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Louis Bonacasa enlisted in the Air Force two days after graduating from Newfield High School in Selden in 2002. He met his wife in the Air Force, his family said.

Newfield High Principal Scott Graviano said teachers recalled how Bonacasa often talked about his desire to serve in the military.

“He knew the direction he was going, and he followed his passion,” Graviano said.

But family members said Bonacasa was recently preparing to end his military career and settle down.

He told Raquel Bonacasa on Saturday that he was looking forward to the delivery of an Army-green Jeep Wrangler when he got home. The SUV was being customized specially for him, she said.

“He said he would be home for our birthdays,” said Gabriela Bonacasa of Farmingville, who turns 28 with her twin sister on April 13. She added: “I always tell him he’s my hero.”

Louis Bonacasa planned to open a smoke shop, following in the footsteps of relatives in Colorado. He and his wife had been preapproved for a home loan a week ago and intended to go house-hunting in the Patchogue area, family members said.

During the airman’s regular video chats from Afghanistan, family members recalled getting to know his roommate, fellow Airman Joseph Lemm. Lemm, 45, an NYPD detective on his third deployment, also died in the suicide attack.

The squadron, which deployed in October, is responsible for “outside the wire” security along the perimeter of Bagram Air Field, the largest U.S. military installation in Afghanistan about 20 miles north of Kabul.

The New York Air National Guard said Bonacasa had previously deployed to Afghanistan from January to June 2013, and to Iraq from June to December 2011.

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His wife and daughter usually spent his deployments at her family home in Hanford, California. That’s where she was Monday when military officials came to the house to tell her about her husband’s death, relatives said.

She called Bonacasa’s mother, Diana, in Farmingville, and the two cried.

“My mom kept screaming ‘No!’ Deborah kept screaming ‘No! This is not real!’ ” Raquel Bonacasa said.

Louis Bonacasa’s body is expected to arrive Wednesday at Dover Air Force Base in Delaware, the family said. Funeral arrangements are pending.

“My brother went out fighting,” Vincent Bonacasa said. “He fought to the end.”

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With Martin C. Evans, Jo Napolitano and Joie Tyrrell