Three people have been arrested in the incident, which took place just after 1 a.m. EDT Sunday at the Sheraton Society Hill hotel.
Part of the melee was captured on video by a 15-year-old hotel guest, Max Schultz, who took a 73-second cellphone video showing police and wedding guests in suits swinging wildly at one another, The Philadelphia Inquirer reported.
Vincent Sannuti, 57, collapsed of a heart attack in the hotel parking lot after ushering his grown children from harm's way and later died at an area hospital.
Police have identified Matthew Sofka, 26, of Westfield, N.J., as the brawl's "main combatant." He was charged with aggravated assault, simple assault, reckless endangerment and rioting.
Officers said they still don't know what exactly set things off.
"Half the time, you don't even know how a fight started," Lt. Ray Evers said. "They all got involved. You really can't tell who's on what side when they're all in suits. It's not like they're wearing opposing uniforms."