Nearly three dozen people have been infected in an E. coli outbreak linked to chopped romaine lettuce from the Yuma, Ariz., region, the Centers for Disease Control and Prevention said on Friday.

The agency said that it had not yet identified a grower, supplier, distributor or brand common to the 35 cases of infection across 11 states, so it urged consumers to avoid any chopped romaine lettuce from the Yuma area.

“If you cannot confirm the source of the lettuce, do not buy or eat it,” the C.D.C. said in a statement. The agency also recommended that restaurants and retailers not serve chopped romaine lettuce from the region.

The people infected so far range in age from 12 to 84 years old. Of the 22 people hospitalized in the outbreak, three had developed a type of kidney failure, according to the C.D.C. No deaths have been reported. Because of an average reporting delay of two to three weeks, illnesses that may have occurred after March 27 have not yet been counted.