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.

WebMD.com described an aortic dissection as 'an abnormal separation of tissues within the walls of the aorta' caused by high blood pressure, family history of the condition, disease of connective tissue, or severe trauma to the chest.

'Aortic dissection results in a weakened blood vessel wall that may also rupture,' the Web site says.

Ritter was best known for his role as Jack Tripper on the long-running television sitcom, 'Three's Company.'

He was the youngest son of Western film star and country music legend Tex Ritter, according to his biography on ABC's Web site.

John Ritter was born on September 17, 1948. He is survived by his wife, Amy Yasbeck, and their daughter, Stella, and three children -- Carly, Tyler and Jason -- from his first marriage to Nancy Morgan.

OMG I am heartbroken to see this!

This was the very first thing I heard when I woke up this morning and my heart just sank

I am so upset by this. I loved him. We watch the repeats of THree's Company all the time.

And Johnny Cash too? Not a great way to start the day.

WOW I cant believe that he passed away...He was so young.....I heard on the radio this morning that ABC already cancelled his show that he was on....

I remember Threes Company...That was my favorite show when i was younger...

i am shocked and sad

I can't believe this!!! It's SO upsetting!!!!!!!!!

Anyone have any good news? Left and right everyone is getting sick and dying!

I'm so sad about this! He was great.

So sad. I still watch the re-runs every night of Three's company.

I am so upset. He is way too young. I was in such shock this morning. He was such a great actor and comic. There will never be another like him

I loved Three's Company and his new show 8 Rules was great too.

he ws so young! just not right.

I am sad . Also, he did the voice of Clifford The Big Red Dog too.

I'm still in shock. I still can't believe he's gone

OMG - i cant believe this - he was so young - this is so sad

I can't believe it. He was so young.

Oh my God, I am so upset!!! I loved him!