A child who became sick from E. coli following a visit to the San Diego County Fair died on Monday.

Reports state that three other children were infected but did not go to the hospital for treatment. The youngest, who died from the disease, was only two years old.

The San Diego County Health and Human Services Agency announced Friday that all four of the confirmed cases were linked to contact with animals. The fair has since closed all access to the animal areas, which includes its petting zoo.

The fair’s Deputy General Manager Katie Mueller told reporters, “Safety is and will continue to be our number one priority.”

San Diego County public health officer Wilma J. Wooten expressed her condolences to the family of the deceased child in a statement released Friday.

“Our sympathies go out to the child that died from this illness. While most people recover from this illness without complications, 5 to 10 percent of people diagnosed with STEC develop the life-threatening kidney infection,” she said.

Del Mar Fairgrounds CEO Timothy Fennell also expressed his sympathies for the grieving family on Friday at a press conference.

“Our hearts, our prayers, our thoughts go out to the family and the friends of this young child,” Fennell said.

He later told reporters, “No contamination has to do with food service or food at all. That’s been verified.”

The Centers for Disease Control and Prevention (CDC) says the symptoms of E. coli, also known as STEC, vary from person to person. However, the most common symptoms include severe stomach cramps, diarrhea, vomiting, and sometimes a low-grade fever.

“Most people with a STEC infection start feeling sick 3 to 4 days after eating or drinking something that contains the bacteria. However, illnesses can start anywhere from 1 to 10 days after exposure,” according to the CDC.

To prevent an infection of E. coli, which is a bacteria found in the intestines of animals and people, food, and the environment, the CDC recommends washing your hands thoroughly after using the bathroom and before preparing food.