TAMPA, Fla. (WFLA) — Buffalo Bills Head Coach Sean McDermott praised the man responsible for giving Damar Hamlin CPR in what experts called an “absolutely vital” move in saving the 24-year-old safety’s life on Monday.

Hamlin suffered a cardiac arrest while tackling Bengals receiver Tee Higgins on a seemingly routine play that didn’t appear unusually violent. Seconds after the hit, assistant athletic trainer Denny Kellington rushed onto the field to begin administering CPR to Hamlin.

“For an assistant to find himself at that position and needing to take the action that he did, and step up and take charge like he did, is nothing short of amazing,” McDermott told reporters during a Thursday press conference.

While Hamlin’s heartbeat was restored on the field, he was transferred to the UC Medical Center for further testing and treatment.

In the days since the cardiac arrest, experts said Hamlin has shown great improvement, responding to doctors’ questions and even communicating with them through writing.

Doctors said Hamlin’s relatively quick recovery would not have been possible had it not been for the “textbook execution” by the Bills medical staff, officials from University of Cincinnati Medical Center said Thursday.

“It just speaks really to the immediate recognition that there was something significantly and seriously wrong by the Bills medical staff,” University of Cincinnati Health physician Dr. William Knight said. “We cannot credit their team enough.”

“You talk about a real leader, a real hero, in saving Damar’s life,” McDermott said while discussing Kellington’s heroic efforts. “As they say, practice pays off and it did in this case.”