The 25-year-old, who is currently serving a four-game ban for breaking rules in relation to the league's substance abuse policy, is said to have suffered a head injury.
According to NFL.com, the injury to Bailey, who has 59 receptions, 843 yards and two touchdowns to his name, is not life-threatening.
The Rams released a statement on Tuesday, which read: "We are aware Stedman Bailey was involved in an incident this evening. We have spoken with Stedman and he is in the hospital in critical but stable condition. We are gathering facts about the situation and will provide updates as we learn more."
Bailey is reported to have been in a car with his cousin and two young relatives when the shooting occurred.