The ambiance at the San Francisco 49ers game became gloomy after a fan collapsed and died at Levi's Stadium on Sunday.

Paramedics, according to a Fox Sports report, were called to Section 221 during the third quarter of the 49ers game against the Broncos. It was noted that a man was having heart troubles. The crowd reportedly heard a whistle then saw the staff hurrying into the section of the stadium.

The same report shared that the emergency case was that of a middle-aged 49ers fan who was taken outside the stadium unconscious in a stretcher.

The man, whose identity was withheld, was pronounced dead on arrival at the San Jose Hospital, Mercury News reported.

Some spectators at the scene said that the sun was shining very hot during the game and that some people needed extra hydration. Authorities have yet to confirm if heat was one of the contributing factors to his death. Cardiologist Cesar Molina said that it could be possible but that he still needs to check on the fatality's history.

It was explained in the Mercury News article that the fan was sitting in the sun-baked stadium adjacent to the visitors' sideline.

"It was really, really hot right there, and he was just pouring sweat," said Craig Love, one of the spectators who was seated near the man.

Love was also able to take a video of the incident after he saw the man passed out beside him. Mercury News said that Love thought the man was just drunk but when he was not responding to wake-up calls of his seatmates which included a hard slap on the knee, a part of the crowd started asking for help.

Stadium officials were reportedly informed of the matter two minutes after the incident. The medical team performed CPR on the man who, according to Mercury News, was still able to let out a loud sound before lying on the ground lifeless.

The 49ers have expressed their plan to make changes to help heat-stricken fans cope with the killer weather during games but it said that there are still no specific details on this plan.

Mercury News said that the next game slated in the stadium will be the 1:00 p.m. match on Sunday. Fans expect that the season opener this coming September 14 is a lot cooler since it will be at 5:30 p.m.

Team officials have advised fans to bring with them sun block, a hat and water for hydration.

"We want to continue to work with our fans to educate them with not just the stadium, but everything that goes into enjoying the game there. The weather is obviously a part of that," said team spokesperson Bob Lange.