Casey Kasem ... the legendary DJ who hosted America's Top 40 for decades, is in dire condition, and a family feud has erupted between Casey's kids and their stepmom.
Jean Kasem -- Casey's wife -- will NOT allow Kerri, Julie and Mike to visit their father, who lives in the exclusive Holmby Hills area near Bev Hills. We're told they've been trying to make contact with their dad for 3 months, to no avail.
Casey -- who is 81 and has advanced Parkinson's -- hasn't been heard from in months.
The kids are outside the house right now ... with a group of friends, family and former co-workers of Casey -- and we're told Jean has just called the cops trying to get them away from the property.
Casey's brother, who is on the scene, tells TMZ Jean has had a strained relationship with Casey's kids for years. The brother says he hasn't spoken with Jean since Casey married her -- 33 years. Kerri, Casey's oldest daughter, tells us Jean has aggressively blocked the kids from the house.
Kerri tells us it's not about money. The kids have all been excluded from Casey's will and they've known that for a long time. She says they just want to see their dad, and they can't.
Kerri tells us she wants to send a message to her dad: "Your children are here for you. We have not abandoned you."