All four students became ill in November, the department said. One of the students had both of his feet amputated after the bacterial illness affected blood supply to his limbs. The freshman lacrosse player remained hospitalized Tuesday.
Officials are concerned about the outbreak of bacterial meningitis, which can be spread through coughing, kissing or prolonged contact. More than 300 students who were in contact with the sick students have been given antibiotics.
Symptoms of meningitis can include fever, headache, stiff neck, nausea and vomiting.
The Associated Press contributed to this report.