Doctors to determine if Hamlin suffered brain damage from lack of blood flow

Buffalo Bills safety Damar Hamlin remains in critical condition Tuesday night after his heart stopped beating during Monday night's game against the Bengals. The 24-year-old suddenly collapsed after making a routine tackle. 

Hamlin got up after the hit for a few moments, but then suddenly collapsed.

"Now all of a sudden you have a heart that was pumping normally as you think of a heartbeat and now that is essentially quitting."

Dr. Camilla Sasson of the American Heart Association in Denver explains after Hamlin's heart stopped beating all blood flow was cut off to his organs. Time is critical.

"Everything you do on the field is what is going to matter the most in whether somebody is going to survive," Dr. Sasson explained.

At first, CPR was performed on the Bills' defensive back. Then an AED, an automatic external defibrillator, was brought out to try to get Hamlin's heart back onto its normal rhythm.

"Is that heart in a rhythm that can be shocked? If it is, then the AED automatically will shock and so when that happens it can take you out of that quivering heart," said Sasson. 

Once the heartbeat is regained then it is time to move the victim to an emergency room. An ambulance transported Hamlin from the field to a Cincinnati area hospital. There, fans lit candles and prayed.

 After all that the game could not go on and was postponed.

Now doctors will try to determine if Hamlin suffered damage from lack of blood reaching his brain.

Hamlin's family thanked first responders, medical personnel and millions of well-wishers for their support, saying they are deeply moved by the prayers, kind words and donations from fans around the country.