Friends were gathering at the Cathedral of St. Thomas More in Arlington County early Saturday to memorialize John Malvar, the 18-year-old who had been dead for 40 days after a skateboarding accident.

But his father, George Malvar, wasn’t there. He didn’t answer his cellphone or home phone, and when several of his friends went to his apartment to find him, no one answered the door.

When the maintenance man unlocked the door, the friends found Malvar dead on his bed. Arlington police, who were immediately summoned, said he died of natural causes. A daughter said he had hypertension and recently had aortic surgery.

“Last night, he was fine,” lamented Raul De Cecco, one of his longtime friends, as he and others who had been planning a celebration of a young man’s life now faced mourning another death. “In his car, we found 50 or 60 rosary beads he was going to give out at the cemetery. There’s a cake he hadn’t picked up yet at the bakery that we were going to have.”

Malvar, 75, a Filipino immigrant who moved to the United States about 30 years ago, had been devastated by the unexpected death of his son June 4 and has spent nearly every day since then with friends. John Malvar was two weeks away from graduating from Washington-Lee High School.

John Malvar died in an accident last month. Family and friends were gathering on Saturday to mark the 40th day since his death, a Filipino tradition that includes a Catholic Mass and a cemetery visit. (Arlington County Public Schools)

“They’re preparing for graduation, and in the prime of his life, he’s taken away with an accident,” his father said at the time. He later added, “I don’t understand why all of this happened.”

According to a Filipino Catholic custom, friends and family gather on the 40th day that a person has been dead.

George Malvar and dozens of others planned to pray at John’s grave site, attend a noon Mass and then celebrate the young man’s life at a party.

John’s death struck the Arlington community hard; he was a well-liked senior at Washington-Lee and had just attended the prom. He was on a skateboard in the 300 block of South Highland Street and had grabbed onto a friend’s pickup when he lost his grip, fell and hit his head. The driver of the truck, another Washington-Lee student, has been charged with reckless driving.

Malvar, whose first marriage ended in divorce and whose second wife died a decade ago, is survived by four sons and two daughters, all but one of whom live in the Philippines. The daughter in the United States, Rowena Korpal of Seattle, said he had worked as an insurance salesman in New York, then moved to Arlington about 20 years ago, where he was a salesmen in the menswear department of Lord & Taylor until his retirement. He also volunteered at St. Thomas More’s school, supervising students during lunchtime and after school.

Hours after learning of George Malvar’s death Saturday, the friends went on with Mass for John Malvar, which drew nearly 40 people, including about a dozen young people.

“As shocking as it is to all of us, when you think about it, George truly missed John,” the Rev. Robert J. Rippy said in his sermon. “In some ways, God has blessed George even though we don’t understand it humanly. . . . All of us need to be prepared, because we never know when God will call us forth.”

Edna Agustin, who cooked a spaghetti dinner for Malvar and her husband Friday night, said after Mass that she was still trying to cope with the news.

“Last night was the happiest I ever saw him,” she said Saturday. “He said it was the best spaghetti he’d ever had in his life. My husband and another friend were kidding him, saying it was the worst they ever had, but it was all gone in a half-hour.”

Shaneena Bitanga, another friend, added that George Malvar was much loved.

“His house was tiny, but his friends were welcome and we spilled out his door,” she said. “He kept all this pain inside, and he never lost his dignity.”