Seventeen staff members were evacuated from the Exeter Hospital operating room in New Hampshire after they began to feel dizzy.
In a statement, Exeter Hospital said staff and patients in the operating room complained of dizziness Friday morning due to "an unknown cause." The hospital said it closed the emergency and operating rooms "out of an abundance of caution."
The Epping Fire Department said it was dispatched for a carbon monoxide problem.
The emergency room, which is located near the operating room, was evacuated as a precaution, CBS Boston reports, even though no patients in that area complained of dizziness.
Aerial footage from CBS Boston showed multiple patients in hospital beds outside the facility.
No odor was detected prior to staff members feeling ill.
"What we know is patients were being treated in the [operating room] with flu-like symptoms when those treating them also started feeling ill, so the OR was shut down and people were moved to the ER for treatment," said town manager Russell Dean. "The same thing happened there, so the ER was shut down and a staging area has been set up outside the main hospital, with patients being transported to area hospitals."
Dean said "source of the issue is being investigated as a possible leak of some kind."