AUSTIN (KXAN) — Four people living in Texas have now become ill after eating romaine lettuce linked to an outbreak of E. coli.

In an update released Wednesday, the U.S. Food and Drug Administration said that a warning about romaine lettuce grown in Salinas, California, is still active.

Across the US, there have now been 102 cases reported in 23 states.

Last month, health officials warned people to stay away from romaine lettuce from Salinas, and it was pulled off the shelves at H-E-B in Austin.

People have been told not to eat the substance if the label does not say where it was grown, while supermarkets and restaurants have been told they should not sell or serve the lettuce.

The warning applies to all types of romaine from the Salinas region, including whole heads, hearts and pre-cut salad mixes.

“We’re concerned this romaine could be in other products,” said Laura Gieraltowski, lead investigator of the outbreak at the U.S. Centers for Disease Control and Prevention.

Officials said their investigation led to farms in Salinas and that they are looking for the source of E. coli tied to the illnesses. Salinas is a major growing region for romaine from around April to this time of year, when growing shifts south to Yuma, Arizona.

Symptoms of E. coli include severe stomach cramps, diarrhea, fever, nausea and vomiting.

Anyone who has symptoms resembling an E. coli infection should contact their healthcare provider.