 Gagnon was undrafted and began his professional career in the ECHL with the Dayton Bombers and scored 61 points in 136 games.He also racked up a total of 665 penalty minutes in his two seasons with the Bombers.This was followed by a spell in the International Hockey League with the Fort Wayne Komets where he scored 7 goals and 14 points in 72 games with 457 penalty minutes.