UPDATE -- Michael Jackson passed away today at the age of 50. Click here for the latest.
We've just learned Michael Jackson was taken by ambulance to a hospital in Los Angeles ... and we're told it was cardiac arrest and that paramedics administered CPR in the ambulance ... and it's looking bad.
He was picked up at his home around 20 minutes ago -- we're told his mother is on the way to visit him.
UPDATE: The 911 call came in at 12:21PM at his Holmby Hills home in L.A.
UPDATE: A Jackson family member tells TMZ Michael is in "really bad shape" and the brothers are headed to UCLA.
UPDATE: We just got off the phone with Joe Jackson, Michael's dad, who says "he is not doing well."