The headquarters building for New Jersey Natural Gas was evacuated late Friday morning when several employees became ill, some of whom felt dizzy or vomited.
The first person to get sick was found lying on a bathroom floor. Other workers in the cubicle area on the second floor of the building said they felt dizzy or started to throw up, spokesman Micah Rasmussen said.
Wall Township emergency responders began an investigation as workers were directed to another building across the street.
Seven of those who felt sick were taken to the hospital.
About 300 people work in the building.