4:07 PM PT -- Karl-Anthony Towns -- Mac's close friend -- just showed up at Miller's home. He stayed for a few minutes before leaving.

Towns -- who said he broke down when he heard the news -- tweeted ... "Not only were you my favorite artist, you was one of my closest friends. The love we had was genuine and the moments we shared were filled with nothing but positivity and laughter. I love you man and I’m sure as hell gonna miss you."

The death of Mac Miller has hit the sports world hard -- with several notable athletes who were fans of his music paying tribute to the rapper Friday.

Steelers superstar Le'Veon Bell -- who had a strong connection with the Pittsburgh native -- tweeted, "NOOO! I do not wanna believe my brother is dead! I cannot take this anymore, life is too short...I just know you’re now in a better place now than this place we call Earth @MacMiller ...I love you bro, and will miss youu 😭"

Another Pennsylvania product -- legendary corner Darrelle Revis -- shared a heartfelt message underneath an old photo of the two, saying, "My heart just dropped when I heard the news about my brother Mac Miller. Our last conversation we had I told you I would come to one of your shows but I never mentioned which one because it was going to be a surprise."

"9 years ago I saw a young man with a gift that would change the world with his voice. I saw a young man who was talented as anybody in the rap game and he was 17 years of age at the time. I remember rushing back home in the off-season to spend time in the studio to be around a creative genius."

"You inspired so many people across the world as an MC from the 412 and one thing I can say is I was here to watch you become a Legend from the very start of your career. To the rap game and to PITTSBURGH we lost a real one but his music will live on forever!!! #kids #longlivemacmiller"

NBA stud Jabari Parker also reflected on how Mac Miller impacted his life with an old photo of the two in L.A., saying, "DAMN MAC. I’m hurt. And the crazy thing is, I don’t even take pictures with my hero’s because the memory is more important than the canvas."

"But this particular day I had to. This day I wasn’t even suppose to be there. But as soon as my boy told me your whereabouts, I rushed over to holla at you. 'Huge fan MAC'. Always will be your fan. RIP brother, one of the greatest to do it!"

Cardinals rookie Christian Kirk gave his thoughts on Twitter, writing, "another talent gone way too soon" and Cowboys WR Cole Beasley -- who also raps -- said, "Mac Miller being gone is hurtin me right now."

Even UFC boss Dana White paid tribute to the musician, posting a photo of Mac Miller and writing, "WOW!!!! Very sad..... RIP."