LOS ANGELES, Aug. 8 (Xinhua) -- An outbreak of salmonella has sickened at least nine people in the U.S. states of California and Colorado, health officials said on Saturday.

    Health departments in the two states linked the outbreak with ground beef products that may be tainted with salmonella.

    The California Department of Public Health said that three people in Orange County and two in Tulare County reported feeling ill. Colorado health officials say at least four people there were hospitalized for related illnesses. All are recovering.

    The tainted beef products are being recalled by a company in Fresno, Central California after the U.S. Department of Agriculture (USDA) issued a food safety warning earlier this week.

    The recall involved 825,769 pounds of ground beef produced between June 5 and June 23 this year.

    This was the biggest beef recall so far this year.

    The beef has been distributed by Beef Packers Inc. to retail distribution centers in Arizona, California, Colorado and Utah.

    The investigation began after a Salmonella outbreak in Colorado. USDA officials traced it back to the Fresno plant.

    The outbreak involves a strain that is especially dangerous. The strain is resistant to antibiotics and may increase the risk of hospitalization and treatment failure.