Zamora was pronounced dead at Loma Linda University Medical Center.
Further details were expected later Thursday night.
The city of Colton released a statement Thursday afternoon:
"It is with deep sadness that the City of Colton announces the passing of Mayor David R. Zamora at approximately 2:00 pm today. Ever dedicated to City business and the community he loved, Mayor Zamora was driving from home to City Hall when he suffered a heart attack, which resulted in a single car accident on La Cadena Avenue with no other persons involved.
" 'As was widely reported just last week following Mayor Zamora's first State of the City address, with love and conviction he felt that the City of Colton has embarked - in his own words - upon a "New Beginning",' said City Manager Rod Foster. 'We are confident that his legacy will be well-served by the City continuing in the spirit of his leadership.'
"Our hearts and prayers go out to his wife, Sarah Zamora, his children, grandchildren, the extended Zamora family and all of his friends and loved ones. Funeral announcements and additional information will be announced when available."