'Descendants' Cast in 'Complete Shock' Over Cameron Boyce's Death Ahead of Third Movie Premiere

The cast of theDescendantsfranchise is reeling in the wake of their costarCameron Boyce‘s sudden death.

A source tells PEOPLE the stars of the global smash franchise are grappling with the realization that Boycedied at the age of 20over the weekend.

“Everyone is in a state of complete shock,” says the source. “The cast had a strong bond and this is unimaginable.”

Boyce,Dove Cameron, Sofia Carson and Booboo Stewart all reprised their roles for theupcoming third installmentin the music-driven story about famous Disney villains’ children wrestling with whether or not they have inherited the evilness of their parents.Descendants 3is set to premiere Aug. 2 on Disney Channel and DisneyNOW.

Descendants 3.David Bukach via Getty Images

“It is with a profoundly heavy heart that we report that this morning we lost Cameron,” a family spokesperson said in a statement to PEOPLE, revealing that his cause of death was related to “an ongoing medical condition.”

“He passed away in his sleep due to a seizure which was a result of an ongoing medical condition for which he was being treated. The world is now undoubtedly without one of its brightest lights, but his spirit will live on through the kindness and compassion of all who knew and loved him,” the family spokesperson said. “We are utterly heartbroken and ask for privacy during this immensely difficult time as we grieve the loss of our precious son and brother.”

Paul Archuleta/FilmMagic

The tributes to Boyce, who also starred in the Disney Channel seriesJessie, have beenpouring in.

“My Love, Light and Prayers go out to Cameron and his Family. Cameron brought Love, Laughter and Compassion with him everyday I was in his presence. His talent, immeasurable. His kindness and generosity, overflowing,”wroteDescendantsdirector Kenny Ortega.

Adam Sandler, who played Boyce’s father in the filmsGrown UpsandGrown Ups 2, also remembered the actor.

“Too young. Too sweet. Too funny,” hewroteon Instagram. “Just the nicest, most talented, and most decent kid around. Loved that kid. Cared so much about his family. Cared so much about the world. Thank you, Cameron, for all you gave to us. So much more was on the way. All our hearts are broken. Thinking of your amazing family and sending our deepest condolences.”

source: people.com