Jennifer Aniston, Courteney Cox, Lisa Kudrow, Matt LeBlanc, and David Schwimmer provided a statement to People, saying, "We were more than just cast mates. We are a family. There is so much to say, but right now we’re going to take a moment to grieve and process this unfathomable loss."

They go on to add, "For now, our thoughts and our love are with Matty’s family, his friends, and everyone who loved him around the world."

TMZ broke the story, Matthew was found unresponsive in his jacuzzi over the weekend after 2 hours of pickleball ... sources told us there were no illicit drugs found at his home, but there were several medications discovered -- including anti-depressants and anxiety meds.

An autopsy has been done, but the results are inconclusive ... and an official cause of death could take months before an answer is discovered.

Since Matthew's passing, fans, friends, and family members have all mourned the loss of the actor -- a memorial was even set up outside the NYC building which was used for exterior shots on "Friends," specifically to portray the place where the pals all lived.