Team officials said he had movement in his limbs and it was not a neck injury. The Colts also said Williams was strapped down for precautionary reasons and will not return to the game.
Williams was injured when Broncos linebacker Deiontrez Mount appeared to make helmet-to-helmet contact with him as Mount rushed a punt and knocked Williams over backward. He remained down for several minutes as he was lifted onto a backboard and had his facemask removed. While he was being treated, players from both teams dropped to their knees.
When Williams was lifted onto the cart, the Colts went over to support their teammate and some Broncos players clapped.
Williams was the second player to leave Thursday's game on a cart.
Broncos quarterback Trevor Siemian was taken to the locker room after injuring his left shoulder. His will not return, either.
Siemian was injured when Colts linebacker Barkevious Mingo drove him into the ground for a 10-yard sack with 2:33 left in the first quarter. Siemian got up and left the field without assistance before being driven into the locker room.
Denver quarterback Paxton Lynch already was inactive for the game because of an ankle injury, leaving Brock Osweiler as the only healthy quarterback on the roster.
Osweiler entered the game on Denver's next series.
Colts running back Frank Gore left the game in the first half with a knee injury. But he returned in the second half and became the second player in league history to record 1,000 yards from scrimmage in 12 consecutive seasons.
Only Emmitt Smith, with 13, has more.
Gore is No. 5 on the NFL's career rushing list.
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