Exeter Hospital in New Hampshire was evacuated Friday morning and extra ambulances were called in after reports of an odor in the emergency room, according to the local firefighters' union.
New Hampshire One reports employees were asked to leave the hospital around 11:30 a.m. when police and other first responders were called.
The Exeter firefighters union tweeted crews were called to the scene for an "unknown odor" in the emergency room.
According to a spokesperson for the hospital, five staff members began showing symptoms like dizziness around 8:30 Friday morning.
The number of patients increased to about 20 as the morning went on and the emergency department and operating room were closed out an "abundance of caution," Deb Vasapoli told Boston 25 News.
Officials say they have not been able to find the source of what is making people sick at the hospital. Some of the patients were transferred to other hospitals in the area.
According to Vasapoli, the only people affected by the symptoms were staff members and they were all from the operating room.