The incident began when the Titans came out of the tunnel and huddled as a team at the Ravens' logo in the middle of the field.
Harbaugh pointed at the huddle while moving toward the center of the field, and Butler yelled back at him. When Harbaugh and Butler got in each other's faces, the Titans players and Ravens coaches separated Harbaugh and Butler.
Titans coach Mike Vrabel pulled his players back to the sideline and spoke with Harbaugh, who remained visibly upset when he walked back to his side of the field. The Ravens players were in the locker room during this time.
This isn't the first time that the Titans began a game in M&T Bank Stadium like this. In last season's 28-12 playoff upset of the Ravens, the Tennessee players also gathered at the Ravens' midfield logo.