The Fresno County Health Department is investigating an E.coli outbreak.
The department says six people have been hospitalized with the strongest strain of E.coli bacteria.
The victims attended three different private events on the same day, with the same food provider.
Clovis Unified School District has confirmed that Clovis West students were among those hospitalized with E.coli.
Saint Agnes Hospital confirms a Clovis West senior was released from the hospital today.
Students say a sophomore also has been released, but a senior football player remains hospitalized.
Health officials say five people went to the emergency room May 21st with the strongest strain of E.coli, after all five attended the same private party May 19th.
Dr. Edward Moreno with the Fresno County Health Department says, "E.coli infections can be very serious. They can quickly lead to dehydration, hospitalization, renal failure, and every year a few percentage will die from their infections."
The department is trying to find the source, and there was a common beef product at all three private events.
Raw meat, especially ground beef, can spread E.coli if not properly handled and cooked. But it's too early to know the source for sure.
Tim Casagrande with the health department says, "There could be coincidences or multiple products. We won't that until the samples come back from the laboratory."
So no products have been recalled.
Casagrande says you won't buy the suspicious food off the shelf, since it was prepared by a food company.
That means it's still safe to buy beef and leafy green vegetables, as long as they are properly handled.
Still, the Health Department is investigating other cases from people who didn't attend the private parties.
Dr. Moreno says, "If people are sick, with severe abdominal cramping and bloody diarrhea, they need to go to the hospital or to their doctor."
The department says to prevent E.coli infection, wash your hands with soap after handling raw meat, and use a new cutting board and utensils.
Also, cook beef to 165 degrees and until there's no pink left in hamburgers. And wash fruits and vegetables thoroughly.
The health department will send its samples for state testing to see if the e-coli is from the same strain.
That will help determine if the cases are linked or a coincidence.