49ers running back Trenton Cannon was taken off the field in an ambulance after suffering a concussion at the start of his team’s game against the Seahawks on Sunday in Seattle.

Cannon was attempting to tackle Seattle returner DeeJay Dallas when his head collided with teammate Talanoa Hufanga’s leg. Cannon’s neck seemed to twist awkwardly. After Hufanga’s initial punch, his head hit another teammate’s leg, causing him to move in the other direction.

The medical team came out to examine Cannon. Shortly after, the medical cart left, followed by the ambulance. Cannon was transferred to a local hospital.

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Cannon appeared to be moving his arms while on the stretcher, as captured in this video:

As Cannon lay on the field, the entire 49ers bench came out to surround him. Seahawks quarterback Russell Wilson and other Seattle players joined in. The players knelt when Cannon was pulled off the field.

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Cannon was diagnosed with a concussion while in the hospital, ESPN reported, and was ruled out for the rest of Sunday’s game. 49ers coach Kyle Shanahan reported after the game that Cannon will remain in the hospital for further observation. Fortunately, Cannon was cleared of other injuries in addition to the concussion.