TROY, Mich. -- Troy Schools sent a letter home to parents that they will not be serving any lettuce to the students until further notice.

E. Coli Scare Stops Troy School From Serving Lettuce

The Michigan Public Health Department issued a health alert for bagged, industrial-sized packages of iceberg lettuce sold through wholesale venues to restaurants and institutions, stating it could be the source of dangerous E. coli bacteria.

The warning was issued Friday when only 26 confirmed E.coli cases in Michigan popped up. Since then, four more cases have been confirmed.

The health department said the sickened people consumed shredded or chopped iceberg lettuce purchased from Detroit-based wholesaler distributor Aunt Mid's Produce Company.

"Today was taco day for our elementary students, but we just didn't serve shredded lettuce," said Tim McAvoy of Troy Schools.

"They're just doing the right thing to be precautious," said parent Debbie Taylor.

Thirty cases of E. coli have been confirmed in Michigan, the state’s Department of Community Health said Monday.

The department released the following data:

Ingham County: 9 cases in MSU students

Lenawee County: 5 cases in a jail

Washtenaw County: 3 cases in UM students

St. Clair County: 1 case

Wayne County: 4 cases

Macomb County: 5 cases

Oakland County: 1 case

Kent County: 2 cases

The department said those who became ill reported symptoms between Sept. 8 and Sept. 19.

Ages of the sick ranged from 11 to 81 years old.

Thirteen of the cases were known to have been hospitalized.

Aunt Mid's released a statement saying they are fully cooperating with the health department and in addition, it is conducting independent testing on the lettuce.

"We received a call and we instantly acted," said Philip Riggio of Aunt Mid's. "We're baffled by this because we just don't know the source."

Despite the preliminary negative test results, the produce company has decided suspend the sale and processing of its iceberg lettuce line.