Firefighters Report Dizziness After Chemical Release In Boston's Financial District

BOSTON (CBS) – Three firefighters required medical treatment following a hamzat incident on Congress Street in Boston.

A smell permeated the halls of 230 Congress Street around 12:45 pm. It came from a fire extinguishing system which was activated on the fifth floor of the 12 story building.

Boston Fire Commissioner Joseph Finn says "there was certainly some kind of event up there that triggered the system." Though he said it's "too premature" to determine what exactly set the system off.

The building remained evacuated several hours after the initial call, forcing 200 people out of their offices.

"The alarms went off, and we evacuated and that's it," said Kathy Howie, who works in the building.

At least 75 firefighters responded to the call. Three of them, who were among the first to respond to the call, were later sent to the hospital after being exposed to the chemical.

"They were exposed. They were feeling a little dizzy, light-headed, nauseous, and so as a precautionary measure they've been transported for evaluation," said Commissioner Finn.

Two of the building's occupants were also evaluated.

Commissioner Finn says the dry chemical agent is typically found in rooms with large computer servers and acts to displace oxygen in the case of a fire.

"It's called FM200. It's an extinguishing agent that's used in, if you will, high valued areas, because it doesn't leave a residue. It doesn't impact or destroy computer systems and stuff like that," Finn explained.

A security guard has been stationed outside of the building to keep anyone from entering.

Employees in the building will be allowed to return to work Thursday.