A teenage girl in California allegedly baked her grandfather's ashes into cookies and handed them out to her school friends, local media reported on Wednesday.

The student is said to have given her baked goods to at least nine students, the Los Angeles Times said, citing police in Davis, near the state capital Sacramento.

Some ate the cookies without knowing about the macabre extra ingredient and were horrified, Lieutenant Paul Doroshov said, according to the Times.

In a bizarre twist, others among the Da Vinci Charter Academy students were fully aware and ate the cookies anyway, Doroshov told the newspaper, adding that he found the claims credible.

Student Andy Knox told local television station KCRA he was on his way into class when the unidentified young baker offered him one of her treats saying they contained a "special ingredient."

"I thought that she put drugs in it or something. So I asked her if like, 'Is this a weed cookie or something?'" he was quoted as saying.

"And she said 'No.' She said it was her grandpa's ashes. And then she kind of laughed. And I was really, I was kind of horrified."

Police are investigating the October 4 incident, according to multiple media reports, but have not made any arrests or taken action against the girl.

The Davis Joint Unified School District said in a statement its students were safe and there was "no health risk" to anyone involved.

"This recent case has been particularly challenging and we have responded appropriately and in the most respectful and dignified way possible," it went on.

"Those who were involved are remorseful and this is now a personal family matter and we want to respect the privacy of the families involved."