The Boston Bruins have fired head coach Bruce Cassidy, general manager Don Sweeney said Monday.

Cassidy had held the position since February 2017, taking over when the Bruins let go of Claude Julien. The 57-year-old Cassidy was behind Boston's bench for 399 games, and leaves with a record 245-108-46.

The Bruins made the playoffs in each of Cassidy's six seasons, including a Stanley Cup Final appearance in 2019. Boston was eliminated in the first round of the 2022 postseason by the Carolina Hurricanes, a seven-game series that ended May 14.

Boston's search for a new head coach will begin immediately.

"Today I informed Bruce Cassidy that I was making a head coaching change," Sweeney said in a statement. "After 14 years working with Bruce, this was an extremely difficult decision. I want to thank and acknowledge Bruce for all his work and success with the Bruins organization. His head coaching record for the Bruins is impressive, and we are appreciative of Bruce both professionally and personally.

"After taking some time to fully digest everything, I felt that the direction of our team for both this season and beyond would benefit from a new voice."

Bruins president Cam Neely said in a statement he has the "utmost confidence" in Sweeney to now "identify the best candidate that is going to help our team reach its full potential."

Cassidy's exit adds to an already-uncertain offseason for the Bruins.

Top-pairing defenceman Charlie McAvoy underwent a left shoulder arthroscopic stabilization procedure in Boston last week and is expected to miss about six months. Matt Grzelcyk also underwent a right shoulder open-stabilization procedure and is expected to be out five months.

Also last month, the Bruins revealed that Brad Marchand will miss the beginning of the 2022-23 season following hip surgery.

Captain Patrice Bergeron, who just won a record fifth Selke Trophy as the NHL's top defensive forward, is an unrestricted free agent and is mulling retirement at age 36.