From CNN:

Emmy-winning actor John Ritter dead at 54

(CNN) -- Actor and comedian John Ritter has died unexpectedly after he was rushed to the hospital for a "dissection of the aorta," his publicist Lisa Kasteler told CNN.

Ritter, who would have turned 55 next week, was the star of the ABC series "8 Simple Rules for Dating My Teenage Daughter."

In a statement, Kasteler said Ritter was rushed to the hospital after suffering from an unrecognized and undetected flaw in his aorta.

Surgeons at the hospital tried to save the Emmy Award-winning actor but were unable to do so, the statement said.

I was a big Three's Company fan when I was a kid. And I remember watching a bunch of it when it was in syndication. And of course John Ritter played a psycho robot on Buffy in recent past.

This also caught my eye because my Grandfather died in a similar way. It was very sudden in his case too. Bleh.