(NewsNation) — Buffalo defensive back Damar Hamlin was in critical condition early Tuesday after the Bills say he suffered a cardiac arrest on the field following a tackle during the first quarter of Monday night’s NFL game against the Cincinnati Bengals.

Hamlin, 24, stood up on his own after the hit but then collapsed. He was given CPR and taken to the UC Medical Center for further testing and treatment.

It was the 24-year-old’s second year with the Bills, following his sixth-round draft pick in 2021. He grew up in McKees Rocks, Pennsylvania, and didn’t go far to play college football at the University of Pittsburgh as a defensive back.

He spent five years of college at Pittsburgh and appeared in 48 games for the Panthers over that span, according to the Buffalo Bills website. 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.

Hamlin played in 14 games as a rookie with the Bills and then became a starter this season after Micah Hyde was injured.

In 2020, Hamlin began organizing an annual Christmas toy drive in McKees Rocks. By early Tuesday, a community toy drive organized by Hamlin had surged to more than $3.3 million in donations. His stated goal was $2,500.

Following his collapse on the field, fellow players, fans and reporters quickly shared their personal stories about Hamlin.

NFL reporter Jordan Schultz described him as a special person, making an enormous impact on his Pennsylvania hometown. He tweeted a video of Hamlin handing out toys during Christmas.

Bills offensive lineman Rodger Saffold, in a post on Twitter, described Hamlin as a “kind, caring, extremely hard worker.” Saffold wrote that Hamlin is “loyal, honest and can always put a smile on your face. He is more than an athlete, he is a son and brother.”

Another video that has been circulating — posted by Buffalo Bills’ reporter Jenna Cottrell — showed Hamlin running to the sideline to give his mom a hug before playing the Cleveland Browns a few weeks ago.

Hamlin’s mother and some other family members were present at last night’s game in Cincinnati, and his mother rode with him in the ambulance to the hospital.

Early this season, Hamlin spoke about how scary it can be to see a teammate suffer a serious injury on the field.

“Real tough. It’s like real-life stuff going on. Life is bigger than football. You just got to lock back in and find that focus to get through these four quarters just to finish the game out and we did that,” Hamlin said in a post-game press interview in September.

Hamlin has previously spoken about his teammate Dane Jackson, who left a game in September after a helmet-to-helmet hit against the Tennessee Titans.

“We just had our prayer, our ‘DB’ prayer we do every Wednesday. He was next time to me and I just grabbed his hand a little harder. You never know like when your last day you get to experience, so I’m just cherishing every moment I can,” Hamlin said in an interview posted by Schultz.

The Associated Press contributed to this report.