SALEM — About 30 people were hospitalized Sunday night after workers at Thermal Circuits Inc. in Salem began feeling ill, triggering a large hazmat response to the building, according to state fire marshal spokeswoman Jennifer Mieth.
There have been no deaths reported, Salem Fire Department Deputy Chief Alan Dionne said.
The response came after Salem fire officials initially were called to Thermal Circuits around 3:30 p.m. Sunday for what appeared to be a chlorine leak. The building was evacuated as the fire department and a hazmat team responded. The building was eventually cleared for employees on the next shift to go inside.
But after entering the building, several employees began having trouble breathing, felt nauseous, and had consciousness issues, Dionne said.
After workers began feeling unwell, there was a “panic” and they began rushing to exit the building, he said.
“They all exited rapidly, which caused a mass hysteria, in my belief . . . a lot of people got very upset and very excited,” he said.
Some people were being carried out, while others were being attended to on the side of the road, he added.
Eighteen people were transported to a local hospital, and 11 were admitted to other hospitals, a Fire Department spokesperson said.
Twenty people were admitted to North Shore Medical Center Salem Hospital, a spokeswoman said shortly before midnight. Nine were transported by ambulance, while 11 were able to check themselves in.
The hospital was going through standard hazmat protocol, she said.
Hazmat crews sampled the air inside, but no chlorine was found.
However, “that doesn’t mean that something didn’t happen earlier,” Dionne said, adding that a regional hazmat team would conduct a thorough investigation through the night.
The issue was contained to the inside of the building, and there was no danger to or evacuation required at nearby properties, a statement from the fire department said.
Officials with the state fire marshal’s office were also en route to the scene, according to Mieth.
Officials from the Occupational Safety and Health Administration and the Department of Environmental Protection were also expected to assist in the investigation.
The building will not be open for business on Monday, Dionne said.
Around 11:30 p.m. Sunday, nearly two dozen response vehicles filled the building’s parking lot. In the center of the scene, flood lights from a hazmat fire truck illuminated the building’s exterior as teams continued their investigation.
Thermal Circuits manufactures surface heaters, air heaters, molded heaters, heater assemblies, and infrared panel emitters, according to the company’s website.Globe correspondents Alejandro Serrano and Abigail Feldman contributed to this report. Jerome Campbell can be reached at firstname.lastname@example.org. Follow him on Twitter @jeromercampbell.