BERWYN, Ill. (AP) — Authorities say 15 people were hospitalized after a substance spill at a suburban Chicago medical clinic.

Berwyn firefighters were called Tuesday to JenCare Senior Medical Center after phenol — a chemical substance used in certain medical treatments and to kill bacteria — spilled in an exam room.

Fire Chief Denis O’Halloran says at the time of the spill there were 35 people in the building, with some experiencing difficulty breathing, coughing and nausea. After first responders arrived, 15 were taken to area hospitals. Their conditions weren’t immediately disclosed.

O’Halloran says the building was evacuated and closed. The clinic won’t reopen until a hazmat remediation company can clean it up and the city’s building department deems it safe.

JenCare president Frank Mancuso in a statement said the company is investigating what happened.