Heidi's Plastic Surgeon, Dr. Frank Ryan Dies Filed under ( Dr. Frank Ryan, Heidi Montag, Jeep, Malibu, Pacific Coast Highway, Ventura County Fire Department )

TMZ has learned ... Dr. Frank Ryan -- a prominent Beverly Hills plastic surgeon to the stars, famous for Heidi Montag's extreme makeover, was killed in a car crash.

According to law enforcement, Dr. Ryan's Jeep went over the side of Pacific Coast Highway yesterday at around 4:30 PM. The Jeep landed on rocks and lifeguards initially tried to help Ryan, to no avail.

Ryan, who was 50, was trapped in the vehicle and had major head injuries. The Ventura County Fire Department tried hoisting Ryan using a helicopter, but the attempt was called off. Ryan was pronounced dead at the scene.

Minutes before the crash, Ryan Tweeted, "After 25 years of driving by, I finally hiked to the top of the giant sand dune on the pch west of Malibu. Much harder than it looks! Whew!"

Ryan's last Tweet, "Border collie jill surveying the view from atop the sand dune." Ryan posted the picture below with his Tweet. Law enforcement tells us the dog was injured but survived.

Credit: TMZ

UPDATE: Heidi Montag just took to Twitter to post her grievances. "I am devastated to hear the news of Dr. Frank Ryan's death. He was the most amazing person I have ever known. He was an angel and changed my life and the lives of everyone he met. He was the most brilliant talented surgeon who will ever exist. Dr. Frank Ryan changed the world."

"My thoughts and prayers go out to his mother, family, friends, and anyone who was ever blessed enough to meet him," she concluded. "He is in a better place."