Player carted off the field on a stretcher at 49ers training camp

SANTA CLARA -- The first serious injury of 49ers training camp happened on Sunday.

The third-string defense was facing the third-string offense in an 11-on-11 team drills. Rookie running back Jordan James carried the ball and ran through a hole on the left side of the offensive line, where tackle Isaac Alarcon had pancaked defensive lineman Tarron Jackson.

When Jackson went down, some of his teammates cheered for Alarcon because his block was so good. But, Jackson stayed on the ground, and Alarcon quickly realized that he was injured. So he whistled for the trainers to come over.

Defensive lineman Tarron Jackson suffers scary injury

Soon, every player on the 49ers was kneeling silently as the trainers worked on Jackson's neck. John Lynch and Kyle Shanahan stood right next to him and seemed to offer him words of encouragement. Then, the trainers carefully lifted Jackson onto a stretcher and carted him off the field.

Here's what Shanahan said about Jackson after practice.

"Always scary when someone gets taken off on a stretcher. But just letting you guys know, he is conscious, inside communicating with us, can feel all his extremities, and they're taking him down to Stanford now just for further testing. So hopefully, we cleared the real scary stuff, and hopefully we'll get some good news on his neck.”

What was Shanahan's message to the team?

“I mean, it’s always hard like that and especially when guys watch that," Shanahan said. "We were close to him, so we could hear him talking, we could see everything moving, so I just told the guys that, which I think eases them up a little bit for the biggest fears and asked them if they're okay to continue to go. They all yelled ‘yes,’ and then we finished our last period and a half.”

Was Jackson conscious when he was on the ground?

"Yeah, which was good," Shanahan said. "I mean, that made it easier for the players, just to hear that part.”