A school on Manhattan's Upper East Side has been shut down after more than two dozen students came down with a mystery illness this morning.

According to the Ramaz School's website, the students were suffering from "a highly contagious but not dangerous virus spread through contact from hand-to-surface and person-to-person."

Ramaz says it decided to take such dramatic action after consulting with the school's pediatrician and the city's Department of Health.

The DOH says it didn't order the closing, but is investigating what's going on at the school which houses more than a thousand students.

One of the school's administrators told NY1 that 53 students and six faculty members were suffering from something that's likely viral, characterized by symptoms like vomiting, diarrhea and low grade fever.

He went on to say that all of those affected go to Ramaz' early childhood center.

Since many of the students who are sick have siblings in Ramaz' middle and upper schools, administrators elected to close all three schools just to be safe.

And because the virus seems so contagious, the school is asking parents to keep their children from going on play dates or visiting each other at home for the next 48 hours.

The school says Ramaz' food service staff has already done a specialized cleaning in case the illness is a result of food poisoning. A specialized top-to-bottom cleaning was also ordered for the lower school building.

School officials said they have not determined when the buildings will reopen.