According to Knighton's Twitter page, he was at Pure nightclub in Jacksonville, but team officials say they are "gathering information about what happened and are not able to further comment at this time."
The Jaguars say in a statement that "our concern and our focus is on Terrance and his health and recovery."
Knighton, a fourth-year player from Temple, has started 45 games in three seasons and has become a staple in the middle of Jacksonville's defense. He reported to training camp overweight and finished with 61 tackles last season. He is hoping for a big season in 2012 in hopes of landing a lucrative, long-term contract.