NCAA: I suppose it a matter of for which player was an injury timeout called for..
Regardless, here's a rule site (from 3-3) for what is to happen after a timeout is taken for an injured player.
Injury Timeout
ARTICLE 5. a. In the event of an injured player(s):
1. An official will declare a timeout and the player(s) must leave the game.
He must remain out of the game for at least one down. When in question,
officials will take a timeout for an injured player.
2. The player(s) may not return to the game until he receives approval of
professional medical personnel designated by his institution.