Seventy schools in France have closed after a spike in suspected coronavirus infections, the French Education Ministry told CNN Tuesday, adding that there have not been any confirmed cases in schools since they re-opened.

The schools “had to close their doors” after suspected Covid-19 cases appeared in the wider community, a ministry press officer told CNN.

“For example, if you take the city of Sens, 25 of the 70 schools we [talked] about are in the same city, because there was one case of [Covid-19] in that city,” the ministry said.

This comes as the country navigates the tricky process of restarting its economy and easing its lockdown without causing a spike in new infections.

Some 40,000 schools have re-opened since last week, France’s Minister of Education, Jean-Michel Blanquer told RTL radio station Monday.

Of the 1.4 million students who have returned to the classroom, 186,000 are middle schoolers in “green zones,” which are French districts where the government has decided the epidemic no longer warrants restrictions to free movement.