Parents are knowingly sending their children who have coronavirus back to classes in Wisconsin, health officials said on Thursday, which could lead to potential school district shutdowns.

“The health department has worked with school districts since spring to make a plan to reopen,” Kirsten Johnson, Washington-Ozaukee public health director, told NBC News. “Never in a million years did we imagine or think to account for parents deliberately sending their sick or symptomatic child to school.”

In Washington and Ozaukee counties, which sit right above Milwaukee, there is a patchwork of fall reopening plans. Johnson said that while many schools offered students the option to go to school five days a week, all of them have been “proactive” in implementing preventative measures like staggered start times, reduced classroom capacity, and required face coverings.

More than two dozen schools in the counties are under investigation where at least one student or staff member has tested positive for Covid-19, according to the Washington-Ozaukee Public Health Department’s dashboard. Out of the 15 school districts, 11 are currently under investigation.

There has been at least one positive or suspected case in all school districts, according to Johnson.

Wisconsin, which has recorded 1,268 deaths, isn’t the first state facing difficulties with parents refusing to follow public health protocols. Connecticut has already sent some school districts back home due to outbreaks. A high school student in Massachusetts tested positive for Covid-19 on Sunday, forcing all students and staff in the positive individual’s classes to quarantine for the next 14 days.

Health officials are advising parents not to send their children to school if they’re sick or showing symptoms, and for schools to continue using attendance tracking software to tally students who test positive for the virus.

Johnson said that the counties would hire more contact tracers and consider advising schools to close their doors if there is an upward trend in cases.

“The human behavior aspect of sending sick and positive children to school is not something we can control, and we never accounted for people completely disregarding basic health guidance,” Johnson said. “We have no tools left, and we just want everyone to be safe.”

“A handful of irresponsible parents could be responsible for closing down entire school districts,” she said.