RIVERSIDE, Calif. — A day after seven people were taken to a hospital when a mysterious white powder was found at a California sheriff’s office, authorities identified the substance as cooking flour.

Officials said the powder was discovered Monday in a letter sent to the Riverside County Sheriff’s Department.

Sgt. Chris Willison said seven department employees were given a so-called quick decontamination — sprayed down with a hose. They were then taken to the hospital as a precaution. None complained of medical problems and all were released a short time later.

The building was evacuated as hazardous materials crews worked to identify the substance. It was later identified as unbleached white flour.

The Press-Enterprise newspaper said Tuesday (http://bit.ly/2vpbtS8 ) that the letter was delivered to an area that handles court services.

A criminal investigation is ongoing.

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