Information about the patients' symptoms, or what caused the students and staff to feel ill, was not immediately available.
HANOVER TWP., Pennsylvania (WPVI) -- A Northampton County school was dismissed early on Friday after multiple students and staff members reported not feeling well.
According to officials, crews arrived to Lehigh Valley Regional Charter School in Hanover Township, Pennsylvania at about noon.
When crews arrived, they found 11 symptomatic patients. A total of 39 people were transported to an area hospital.
The building, which houses seventh through twelfth grade students, was evacuated "out of an abundance of caution," but normal operations continued at the other buildings, where younger students are taught.
Hazmat crews were also called to the scene to monitor the air.
Authorities did not disclose details on the symptoms the ill people were dealing with, and it wasn't immediately clear if anyone had suffered serious injuries.
The charter school has 1,825 students who come from 16 school districts in the area.
The Associated Press contributed to this report.