Jayden Daniels Suffers Gruesome Elbow Injury During 'Sunday Night Football'

1:18 PM PT -- Dan Quinn is dealing with some remorse Monday after everything that went down with his franchise QB ... saying while the drive that Daniels got injured was set to be his last of the game -- he wished he pulled him out sooner.

Washington Commanders star Jayden Daniels went down with a gut-wrenching elbow injury during "Sunday Night Football" ... an ailment that will keep him sidelined indefinitely.

The moment went down with just under eight minutes left in the home loss to the Seattle Seahawks ... with the Commanders down by 31 points.

Washington was positioned just a few yards from the end zone as Daniels faked a handoff and scrambled ... but when Seattle linebacker Drake Thomas went for the sack, the quarterback's arm bent in the wrong direction.

If you want to check out the play ... click here -- but it's tough to watch.

Players and fans in attendance were clearly shocked by what happened ... and Daniels was definitely feeling pain.

A cart was brought out on the field ... but the second-year signal-caller ultimately elected to walk off on his own accord in an air cast.

According to reports, Daniels is believed to have a dislocated left elbow ... although it's unclear if his season is over.

After the game, Commanders coach Dan Quinn was asked why Daniels -- who has dealt with two other injuries this season alone -- was still in the game ... and he explained the play wasn't drawn up that way.

"You don't want to think that way where an injury could take place," Quinn told reporters. "It wasn't a designed read or play to that spot. If we run it 50 times, it's either a handoff or throw 50 times."

"So, yeah, it's a bummer, man."

Regardless, the decision to keep him on the field during a blowout is getting scrutinized on social media.