Marty Smith, legendary motocross rider, dies in California dune buggy accident

(CNN)Marty Smith, a prolific motocross rider known for winning 18 career national motocross titles, has died.

He was 63.

Smith and his wife Nancy were killed in a dune buggy accident in the California desert on Monday, close friend Lee Ramage confirmed to CNN.

Ramage and wife Tammi were in the buggy with the Smiths, riding through the Imperial Sand Dunes in California, when the vehicle rolled over. Lee Ramage and Tammi were unhurt.

They stayed with the Smiths in their last hour while the first responders arrived, he wrote in a Facebook post.

“He was my best friend and I did all I could to save them,” Ramage told CNN over the phone. “It breaks my heart to know I couldn’t save them