SAN DIEGO — Behind the police tape, a white coroner’s van sat in front of a garage on the 600 block of South The Strand. It waited to collect the body of Junior Seau, a linebacker among the most feared in NFL history, father to three teenagers, son to the mother who wailed long and loud on Wednesday.

Earlier in the day, according to the Oceanside Police, Seau’s girlfriend went to the gym. When she returned, she found Seau in a bedroom, a gunshot wound to the chest, a revolver found near his body but not a note. He was 43.

The police are investigating Seau’s death as a suicide, Lieutenant Leonard Mata said, adding that they do not expect to finish the investigation until next week.

Outside the house, with its brick front and chairs upstairs on the deck pointed at the nearby ocean, some in the crowd that had gathered tried to make sense of what happened and could not. Here was a linebacker who played 20 seasons in the NFL for three teams, who made 12 Pro Bowls and went to two Super Bowls and was named to the 1990s All-Decade Team by the Pro Football Hall of Fame. Here was a man who grew up here and starred close by with the Chargers for much of his professional career beginning in 1990.

The subject of Seau and how he changed or not in recent years appeared to make his friends uncomfortable. They knew that Seau sustained minor injuries in October 2010 when he drove his sport utility vehicle off a beachside cliff in Carlsbad, Calif., where it landed some 100 feet below the roadside.

Earlier that day, Seau was arrested on suspicion of domestic violence. Reports at that time said Seau’s live-in girlfriend told the police Seau assaulted her during an argument. Friends and the police declined to speculate about Seau’s relationship with his girlfriend.

The NFL, the NFL Players’ Association and each of the three teams Seau played for released statements on Wednesday. All said they were deeply saddened.

“Of all the players I’ve been around, he’s the one who makes you most proud,” said Bobby Beathard, once the general manager of the Chargers. “It’s just sad. It’s hard to believe that now there’s no Junior.”