LOS ANGELES (KABC) -- Bills safety Damar Hamlin is in critical condition after he collapsed on the field Monday night, the NFL said, and Buffalo's game against the Cincinnati Bengals was suspended.
Hamlin was administered CPR on the field, ESPN reported, and he was surrounded by teammates, some of them in tears, after he was hurt while tackling Bengals receiver Tee Higgins.
Dr. Anthony Cardillo, an ER specialist in Southern California, offered his insight into what he saw examining the hit and how Hamlin reacted to it.
"What we can tell is the event was most probably secondary to that hit," Cardillo said.
When talking about the injury, Cardillo mentioned the "R-on-T" phenomenon, explaining:
"This is a phenomenon that when the heart is going between its beats, as that heart is depolarizing and then repolarizing, if you have traumatic trauma to the chest, at a very specific moment as that heart is repolarizing itself, you can go into a lethal ventricular arrhythmia, and that's what it looks like happened," Cardillo said.
Dr. Anthony Cardillo's full interview can be viewed in the media player above.
Hamlin spent five years of college at Pittsburgh - his hometown - and appeared in 48 games for the Panthers over that span. He was a second-team All-ACC performer as a senior, was voted a team captain and was picked to play in the Senior Bowl.
He was drafted in the sixth round by the Bills in 2021, played in 14 games as a rookie and then became a starter this year once Micah Hyde was lost for the season to injury.
By late Monday night, a community toy drive organized by Hamlin had surged to more than $900,000 in donations. His stated goal was $2,500.
The Associated Press contributed to this report.