Public health investigators have not identified a common supplier of ground beef that’s the likely source of a salmonella outbreak in six states.

The Centers for Disease Control and Prevention says that of the 10 Salmonella Dublin infections reported, one person in California died and eight were hospitalized. The illnesses are more severe than expected for salmonella, the agency says.

No recall had been issued to date. CDC did not warn people to avoid ground beef. It reminded people to cook the meat thoroughly and clean up well after handling raw beef.

“CDC is not advising that consumers stop eating thoroughly cooked ground beef, or that retailers stop selling ground beef,” the agency’s investigation notice says.

CDC, public health and regulatory officials in several states, and the U.S. Department of Agriculture’s Food Safety and Inspection Service are investigating.

The illnesses started in August and September. People in Colorado, Kansas, Iowa, Texas and Oklahoma also became sick.

Usually about 20% of people infected with salmonella need hospital care, much lower than the eight of 10 hospitalized in this outbreak. Salmonella can lead to a more severe bloodstream infection, and half of the ill people had the bacteria in their blood.

CDC used the PulseNet system to complete DNA fingerprinting on salmonella bacteria from the ill people. It found the samples are closely related genetically, meaning the infections are more likely caused by a common source.

The people who got sick reported eating different types and brands of ground beef purchased in many locations.

Lab testing identified the Salmonella Dublin strain in repackaged leftover ground beef from an ill person’s home. Salmonella closely related to the bacteria in the ill people has also been identified in six samples of raw beef products from slaughter and processing facilities. FSIS collected those samples in routine testing. “These results provide more evidence that people in this outbreak got sick from eating ground beef,” the CDC says.

CDC will update the public if more information becomes available.