(CNN) Authorities are on the hunt for the man who violently attacked a 91-year-old widower with a large rock as he was visiting his wife's gravesite, police said.

The suspect "took property from the victim" and then fled on foot and later a bike, the Santa Clara Police Department said , calling the attack "unprovoked and ruthless."

The attack took place at the Mission City Memorial Park cemetery on the morning of September 14. The victim was taken to a nearby hospital for treatment.

Police said they believe the attack was an isolated incident, but urged the pubic to report "any suspicious activity."

The suspect was described as a 35 to 50-year-old Hispanic or Latino male, about 6 feet tall with a medium build, police said.

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