SANTA CLARA — A 49ers fan died of an apparent heart issue Sunday after collapsing in front of dozens of other Niner faithful during the team’s first game at Levi’s Stadium, authorities said.

A team of paramedics swarmed Section 221 during the third quarter of the preseason game against the Denver Broncos after the command post was notified of a man who was suffering from a cardiac emergency, the Santa Clara Fire Department said. The crews administered CPR, ripped open his shirt and took the man out on a stretcher.

The fire department rushed him to O’Connor Hospital in neighboring San Jose, but was pronounced dead by emergency room physicians.

A reporter from this newspaper who was nearby when the emergency happened heard a whistle blow around 3:05 p.m. and several event staffers rush to the section, followed by fire department paramedics. Crews blocked off access to the section’s staircase, and within five minutes firefighters had taken the middle-aged man in a gold 49ers jersey out on a stretcher in front of a small crowd that had gathered around. The man, who was not immediately identified, was not moving and was unconscious.

Emergency officials escorted by about a dozen stadium employees whisked him down another flight of stairs and toward an ambulance. Just like that, the section was reopened and the crowd dispersed.

It was the third death at the stadium site but the first since the $1.3 billion Santa Clara stadium had opened. Two workers died during construction: In October, 60-year-old delivery driver Edward Lake II was fatally struck while unloading building materials, and in June 2013, 63-year-old Donald White was killed after being hit by a counterweight in an elevator shaft.

Last season, 32-year-old fan Kevin Hayes fell to his death from a pedestrian overpass at the 49ers regular season opener at Candlestick Park in September.

The fan who died Sunday was sitting in the sun-baked part of the stadium, near the top of the lower bowl behind the visitor’s sideline, where temperatures reached 80 degrees and sent many fans to the shady concourses. The heat also prompted an unusually high number of calls for emergency services, team officials said. But it wasn’t immediately clear if the heat contributed to the man’s collapse.

“The 49ers organization is deeply saddened to hear of the passing of one of our fans earlier today,” the 49ers said in a statement. “We would like to extend our heartfelt condolences and prayers to his family and friends in this time of sadness.”

The death was a sad ending to a stadium opening that was otherwise mostly uneventful, with few major off-the-field problems during the 49ers 34-0 loss to the Broncos.

Staff writer Katie Nelson contributed to this report. Contact Mike Rosenberg at 408-920-5705. Follow him at Twitter.com/RosenbergMerc.