INDIANAPOLIS -- The Colts on Tuesday suspended receiver Isaiah McKenzie and cornerback Tony Brown for three games for "conduct detrimental to the team," sidelining both players until the end of the regular season.

The club did not disclose what behavior led to the decisions, but a source told ESPN the nature of the violations rose to a level where severe punishment was warranted.

Suspensions by individual NFL teams are rare. Most suspensions are handed down by the league for violations of the personal-conduct and drug policies or violations of playing rules related to the health and safety of players.

McKenzie and Brown were healthy inactives during Saturday's Colts win over the Steelers. McKenzie and Brown usually play backup roles, but they have had important functions throughout the season.

McKenzie played in all 13 games before Saturday and had been the team's primary return man. Brown played in 12 games this season and has been a key special teams contributor, playing 71% of the team's special teams snaps this season.