Buffalo Bills safety Damar Hamlin suffered a cardiac arrest against the Cincinnati Bengals on Monday Night Football and was in critical condition Tuesday morning.

The game was suspended after Hamlin, 24, was given CPR on the field and transported to University of Cincinnati Medical Center. It was later postponed with no decision on if and when the game will resume.

Here's what we know about Hamlin's life-threatening injury:

What condition is Damar Hamlin in at the hospital?

The NFL announced that Hamlin was in critical condition when the game was postponed at 10:01 p.m.

The Bills announced shortly before 2 a.m. Tuesday that Hamlin suffered a cardiac arrest. His heartbeat was restored on the field and was transferred to University of Cincinnati Medical Center for further testing and treatment. He is sedated and remains in critical condition.

Why did Damar Hamlin collapse?

Buffalo safety Damar Hamlin was injured while tackling Cincinnati wide receiver Tee Higgins with 5:58 remaining in the first quarter. Higgins lunged into Hamlin's chest and the safety wrapped his arms around Higgins' neck as they spun to the ground.

Hamlin got to his feet for about three seconds, took two steps and then collapsed, landing hard on his back and head. An official standing near Hamlin immediately stopped play and signaled an injury timeout.

More:Bills safety Damar Hamlin collapses on field, game against Bengals postponed

What medical treatment was Damar Hamlin given on the field?

An ambulance was rushed to the field and first responders delivered CPR to Hamlin for nine minutes. He was given oxygen and an automated external defibrillator (AED) was used in an attempt to restore his heart rhythm to normal. Hamlin was taken to University of Cincinnati Medical Center, the region's only adult level 1 trauma center.

What was the timeline of Damar Hamlin's injury?

• 8:55 p.m.: Damar Hamlin was injured.

• 9:18 p.m.: The game was temporarily suspended.

• 9:25 p.m.: The ambulance left the stadium to transport Hamlin to University of Cincinnati Medical Center.

• 10:01 p.m.: The game was officially postponed.

More:Monday Night Football between Bills-Bengals postponed after injury to Damar Hamlin

Did Damar Hamlin's mom ride with him to the hospital?

Yes. Hamlin had family in attendance at the game in Cincinnati, including his mom, Nina. Hamlin's mother came down from the stands and was allowed onto the field while Hamlin was being tended to by medical personnel. She accompanied her son to the hospital in the ambulance.

Hamlin has credited his mom, who gave birth to him at age 16, and dad with being dedicated to him and instilling a strong work ethic.

More:Who is Damar Hamlin, Bills player taken in ambulance on Monday Night Football?

2021: Bills rookie Damar Hamlin stared down childhood adversity and now has a shot in the NFL

How much has been donated to Damar Hamlin's toy drive GoFundMe?

Damar Hamlin began a holiday toy drive for kids in his hometown of McKees Rocks, Pennsylvania, while a senior at the University of Pittsburgh. Fans found the GoFundMe set up by Hamlin two years ago and began pouring in donations on Monday evening. The fundraiser had an initial goal of $2,500. It had raised more than $3 million by 2:30 a.m. Tuesday.

Here was the description for the GoFundMe:

As I embark on my journey to the NFL, I will never forget where I come from and I am committed to using my platform to positively impact the community that raised me.  I created The Chasing M's Foundation as a vehicle that will allow me to deliver that impact, and the first program is the 2020 Community Toy Drive.

This campaign gives you the opportunity to contribute to our first initiative and positively impact children who have been hardest hit by the pandemic.  100% of the funds raised will go toward the purchase of toys for kids in need. The time to act is now, as we will be distributing toys on December 22nd from 3:30 to 5:30 PM from Kelly and Nina's Daycare Center at 800 Russellwood Ave., McKees Rocks, PA 15136.  

If you are not able to contribute monetarily, you can support this initiative in other ways.  We are accepting donated toys at the Daycare Center or simply spread the word by sharing this fundraiser on your social channels.

Thank you so much for supporting me on and off the field.  I am grateful to have the opportunity to work with you to help make the holiday season a little brighter for the kids in our community.

Damar HamlinThe Chasing M's Foundation

How did Bills players react to Damar Hamlin's injury?

The Bills team came off the sideline to kneel or stand around Hamlin as he was initially treated. Once the severity of his condition was apparent, several Bills players cried on the field and sobbed into towels. Other players prayed and hugged each other. The team kneeled in a circle and prayed after Hamlin left in an ambulance.

What have the Bills said about Damar Hamlin's injury?

"The thoughts and prayers of all of Bills Mafia are supporting you, Damar," the Bills tweeted at 9:16 p.m. with a photo of players and coaches praying on the field as Hamlin was taken to the hospital. The organization tweeted a similar photo surrounded by a collage of tweets from NFL players and teams wishing Hamlin well.

"Please pray for our brother," Bills quarterback Josh Allen tweeted at 11:19 p.m. Monday.

Did the Bills fly back to Buffalo from Cincinnati?

Most of the team flew back to Buffalo early Tuesday morning. Several players stayed behind in Cincinnati so they could hold vigil at the hospital, NFL Executive Vice President of Football Operations Troy Vincent said.

Who visited Damar Hamlin at the hospital?

Buffalo Bills wide receiver Stefon Diggs was seen crying on the field as first responders tried to resuscitate Hamlin. A couple hours later Diggs was seen walking into University of Cincinnati Medical Center. ESPN showed Diggs in the parking lot before he gained access to the building. A police officer wasn't going to let Diggs in, ESPN reporter Coley Harvey said.

"I have to be here for my teammate," Diggs reportedly told the officer, who then let him in.

The University of Cincinnati Medical Center is about 5 miles from Paycor Stadium. Bengals head coach Zac Taylor was also seen at the hospital.

More:Stefon Diggs gets ride to Cincinnati hospital to visit Damar Hamlin

Did fans gather at the hospital?

Yes. Fans held vigil outside of the University of Cincinnati Medical Center to support Hamlin. Bengals and Bills fans joined hands, linked arms and prayed for Hamlin. They left candles and signs outside of the hospital.

More:Damar Hamlin injury: Fans hold vigil at hospital after seemingly routine hit turns tragic

Did Damar Hamlin have a heart attack?

No. Cardiac arrest is not the same as a heart attack.

A cardiac arrest is when a person’s heart suddenly stops pumping blood and they stop breathing normally. The heart needs to be restarted and cardiac arrest can be fatal within minutes. Between 70% and 90% of people who have a cardiac arrest outside of a hospital die − often within minutes − before reaching a hospital, according to the Centers for Disease Control and Prevention. Risks to heart or brain damage after a cardiac arrest are high even with immediate treatment.

According to the National Heart, Lung, and Blood Institute, a person may be having a cardiac arrest if they:

A person may be having a cardiac arrest if they:

• Collapse suddenly and lose consciousness (pass out)

• Are not breathing or their breathing is ineffective or they are gasping for air

• Do not respond to shouting or shaking

• Do not have a pulse

A heart attack is when blood flow to the heart is blocked, though many cardiac arrests in adults happen because of a heart attack.

What is commotio cordis?

Commotio cordis is when blunt trauma to the chest results in an irregular heart rhythm, ventricular fibrillation, in an otherwise health heart. It often leads to sudden death. It is seen mostly in youth athletes in sports with projectiles that can strike participants in the middle of the chest. Baseball is the most common sport in which commotio cordis occurs. The blow point is near the heart's left ventricle at a precise moment in the heart's rhythm.

"The athlete will typically stumble forward for a few seconds, which is followed by unconsciousness, no breathing, and no pulse," according to the University of Connecticut's Korey Stringer Institute.

The key to resuscitation is rapid, direct current defibrillation using an AED.

Survival rate drops precipitously with each passing minute and falls to 3% when resuscitation is delayed beyond three minutes, according to a National Library of Medicine study. Data gathered using the commotio cordis swine model suggest that defibrillation within 1 minute of ventricular fibrillation onset results in a 100% survival rate and that defibrillation after 2 minutes results in an 80% survival rate, MedScape says.

Will the NFL reschedule the Bills-Bengals game?

It is not known if the Bills-Bengals game will resume. It has not been rescheduled.

“There’s nothing in consideration right now,” said Jeff Miller, the NFL's executive vice president of communications, public affairs and policy during a conference call with media early Tuesday morning. “Our concern is for the player and his well-being. At the appropriate time, I’m sure that we’ll have a conversation around the next steps regarding the game.”

More:NFL says resuming game was never an option after Damar Hamlin collapsed

What did Skip Bayless tweet about Damar Hamlin?

The NFL said it never considered finishing the game on Monday. FS1 talk show host Skip Bayless came under fire for suggesting the league wouldn't, or shouldn't, postpone the game.

No doubt the NFL is considering postponing the rest of this game - but how? This late in the season, a game of this magnitude is crucial to the regular-season outcome ... which suddenly seems so irrelevant," tweeted Bayless.

Several prominent athletes criticized Bayless' tweet and called for his firing. Bayless later apologized and tried to clarify his tweet.

“How do you resume play after you’ve seen such a traumatic event occur in front of you in real time?” said Troy Vincent, the NFL executive vice president of football operations. " It never crossed our mind to talk about warming up to resume play."

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Who is Damar Hamlin?

Hamlin is a second-year safety with the Bills. He was selected in the sixth round of the 2021 NFL Draft by Buffalo out of the University of Pittsburgh. Hamlin overcame losing multiple friends to gun violence and his dad to prison to become a feel-good story to make the Bills.

He saw action in 14 games as a rookie, making two tackles. Hamlin was thrust into a starting role in September after Micah Hyde went down with a season-ending injury. Hamlin was starting his 14th game in 2022 and has 92 tackles and 1.5 sacks.

Hamlin was a four-star high school prospect and received dozens of Division I offers, including Notre Dame, Ohio State, Penn State and Clemson. He opted to attend his hometown college. Hamlin is from McKees Rocks, Pennsylvania, which is 7 miles from the University of Pittsburgh campus. He had 290 tackles and six interceptions in his Panthers' career and was named second-team All-ACC as a senior.

This article originally appeared on Rochester Democrat and Chronicle: Damar Hamlin in critical condition after cardiac arrest during game