Ten staff members were taken to the hospital after they started feeling sick at the Epping Regional Health Center, according to an article on the WMUR website.
Employees reported feeling dizzy, lightheaded, and tightness in their chests.
The building was evacuated as a precaution, and 10 workers were transported to Exeter Hospital.
Initially, firefighters thought carbon monoxide might have been to blame, but it was ruled out. The building was also checked for flammable gases, but none were found.