The Kenyan Health Ministry issued an alert Friday because of an outbreak of an unknown disease in western Kakamega County that has killed four people.

The disease was discovered in the Mukumu Girls and Butere Boys high schools, with 627 patients ill as of April 14, Director General for Health Patrick Amoth said in a statement.

“Unfortunately, we have lost 4 patients to this illness. We at the Ministry of Health send our heartfelt condolences to the families who have lost their loved ones,” said Amoth.

The Health Ministry said the disease presents fever, abdominal pain or cramps, vomiting and diarrhea.