A group therapy session in Berlin turned violent Tuesday when one participant punched a counselor in the face and stabbed another member of the group, according to Winslow Township police.

Ryan McCausland, 32, of Collingswood, was arrested in the incident that took place at Twin Oaks Community Center shortly after 4:30 p.m. Sept. 16.

McCausland allegedly stood up during the therapy session and punched counsellor Adrien Chavanon, 28, of Berlin, in the face with a closed fist, according to police who say the attack was unprovoked.

Another member of the group — Raymond DiDonato, 46, of Stratford — wrestled McCausland to the ground in an attempt to subdue him, say police.

At that point McCausland allegedly produced a folding pocket knife and stabbed DiDonato once in the back and twice in the stomach.

Police say a third member of the group — Carl Morrison, 24, of Blackwood — grabbed McCausland's arm and pried the knife away to prevent further injury to DiDonato or others, say police.

DiDonato was transported to Cooper University Hospital where he underwent surgery for his wounds.

McCausland was charged with multiple counts of aggravated assault and weapons charges and placed in Camden County Jail on $100,000 cash bail.

Mark Daniels may be reached at mdaniels@southjerseymedia.com. Follow him on Twitter @dannypapers. Find the South Jersey Times on Facebook.