BOSTON (AP) — A man who died at a New England Patriots home game last weekend after he was punched at least twice in the head did not suffer a “traumatic injury” in the stands but had a medical issue, authorities in Massachusetts announced Wednesday.

Police and safety personnel responded to the upper deck at Gillette Stadium shortly before 11 p.m. Sunday and found Dale Mooney, 53, of Newmarket, New Hampshire, “in apparent need of medical attention,” the Norfolk County district attorney’s office said in a statement Monday.

Mooney was taken to a hospital, where he was pronounced dead.

“Our investigation has included numerous law enforcement interviews and the examination of multiple angles of video capturing the scuffle prior to Mr. Dale Mooney’s collapse during the Sunday night game at Gillette Stadium,” the district attorney’s office said in a statement.

“Preliminary autopsy results did not suggest traumatic injury, but did identify a medical issue,” according to the statement. “Cause and manner of death remain undetermined pending further testing.”

The district attorney’s office did not provide any details on Mooney’s medical issue.

In interviews with several local media outlets, Joey Kilmartin said he saw Mooney, a Patriots fan, confront a Miami Dolphins fan who he had been arguing with during most of the game, which the Dolphins won.

“He basically engaged in mutual combat with another fan,” Kilmartin told The Boston Globe. People tried to separate the two, he said, but “then a man in the Dolphins jersey reached over and he connected with two punches to the victim’s head. It wasn’t something crazy or out of the ordinary until, 30 seconds later, the guy wasn’t getting up.”

Mooney’s wife, Lisa Mooney, said she feels numb and wants answers about how her husband died.

“I just can’t even believe this is for real,” she told WCVB-TV. “I want to know what happened. What caused this?”

Gillette Stadium officials said they were “heartbroken” by the death of Mooney, who they described as a lifelong Patriots fan and 30-year season ticket member.

“We continue to work with local authorities to assist them with their ongoing investigation,” according to the statement. “We extend our sincerest sympathies and heartfelt condolences to Dale’s family and to all those who are mourning his loss.”

Fan violence at sporting events, especially among rival supporters, is a long-running problem. In 2011, paramedic and San Francisco Giants fan Bryan Stow was beaten in the Dodger Stadium parking lot.

Two Los Angeles Dodgers fans punched Stow, who fell to the pavement and suffered severe head injuries. He was awarded about $14 million when a jury found the team was negligent. The attackers received prison sentences.