At least 64 people across nearly two dozen states have been sickened by a salmonella outbreak linked to raw oysters, the Centers for Disease Control and Prevention said.

As of Wednesday, Dec. 24, no deaths had been reported in connection to the outbreak, but at least 20 people were hospitalized, the CDC said in a press release one day earlier. No recall has been announced tied to the illnesses.

It's not clear how many potentially contaminated oysters were sold, and officials said a common source of the oysters had not been identified by the CDC and Food and Drug Administration, which is also investigating.

"People in this outbreak are being hospitalized at a higher rate than expected when compared to other Salmonella outbreaks linked to oysters," the CDC wrote in its release. "State and local public health officials are interviewing people about the different foods they ate in the week before they got sick."

Of the 27 people interviewed, 74% of them reported eating raw oysters.