Health officials have confirmed three more cases of New Jersey residents infected with salmonella linked to tainted tomatoes, WNBC reports.

The three new cases, reported Tuesday, come days after the state Department of Health and Senior Services reported the first case linked to an outbreak that has sickened at more than 500 people nationwide.

Officials said the four people – a 7-year-old from Monmouth County, a 2-year-old from Bergen County, and two women, 34 and 41, from Camden County – got sick from May 23 to June 3.

The U.S. Food and Drug Administration has linked the outbreak to consumption of some raw red plum, red Roma, round red tomatoes, and products containing these raw tomatoes.

State officials have begun random inspections of wholesale produce processors and distributors to check the source of tomatoes shipped into New Jersey. They’re also looking at companies’ record-keeping practices and handling procedures.