Sean Ross Sapp of Fightful has since confirmed that the attacker is 26-year-old Zach Madsen, an amateur mixed martial artist. PWInsider confirmed the name in their report as well.
Sapp went on to further state in a published report that he spoke with one anonymous MMA competitor who knows Madsen, with the fighter saying that Madsen, "...seemed harmless and nice, but often didn't make sense."
Madsen rushed into the ring where Hart and niece Natalya (accepting induction on behalf of her late father, Jim "The Anvil" Neidhart) were standing at the podium. He tackled Hart in a waistlock before the pair were quickly descended upon by various wrestlers and nearby persons, including The New Day, Dash Wilder, Heath Slater, Harry Smith, Braun Strowman, and Travis Browne, as well as security personnel.
Madsen was quickly subdued by the intervening wrestlers and dragged off, with the aid of police. After the hysteria settled, Hart and Natalya then calmly carried on with their speech without any further incident.