DEVELOPING: Another Evacuation At Johnson City Municipal & Safety Building

UPDATE 5:24 p.m. Firefighters now think they know what made Johnson City employees sick Monday. Suprisingly, crews say the strange odor that's been plaguing the building for the last two weeks was not the problem. After testing 30 Johnson City employees and the building itself, firefighters discovered low levels of Carbon Monoxide. According to Assistant Fire Chief Chris Williams, the toxic gas was responsible for sending people to the hospital. However, Carbon Monoxide has no odor. So what about the mysterious smell?

"The odor is a mystery," Williams said. "We're still at an unknown at this point."

Firefighters plan to visit the building again Tuesday. Williams says they will be equipped with even more monitors.

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UPDATE 1:04 p.m.///// According to officials, three employees have now been taken to Johnson City Medical Center as a result of the strange "vaporous odor" at City Hall. However, those three people also have shown traces of carbon monoxide after being transported to the hospital. All three will be treated and released, according to hospital officials.

Crews working to find the source of the vapor were surprised to hear this, since carbon monoxide is an odorless gas. It is possible, then, that there is more than one cause of the complaints. However, no concrete evidence has revealed the source of the smell, or the sickness.

UPDATE at 11:07 a.m.: Two employees appear to be headed to the hospital by ambulance. Some employees can be seen holding their heads, apparently dizzy. Others are putting cool cloths on the heads. As many as 7 employees have been affected. Water, sewer, and tax payments will be received on the main floor in the lobby.

UPDATE at 11:04 a.m.: Follow Nate Morabito's updates from the scene on Twitter: nmorabito

UPDATE at 10:51 a.m.: 11 Connects' Nate Morabito reports the Johnson City finance department office on the the lower level of city hall was evacuated after employees once again complained of nauseous headaches and a "metallic taste" in their mouths. As many as 8 employees were being examined at city hall by emergency crews, Morabito learned. A make-shift office was being set up on the second floor of city hall for customers to pay bills.

Here's the first report:

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Just four days after a suspicious smell sickenend some employees and forced the temporary closure of the bottom level of the building, crews emptied a portion of the building again today.

11 Connect digital journalist Nate Morabito reports caution tape has been placed over the lower level entrance to city hall, the same entrance where "danger" tape was used to block entrance last Thursday. He first learned of problems at "city hall" as its commonly called just after 10 a.m. Monday.

According to the Johnson City Medical Center, 4 employees were treated and released from the hospital after complaining about a strange smell that caused them to feel ill. Tests of the building by the Johnson City Fire Department found no source for the smell, and the building was re-opened for use by late Thursday afternoon.

Look for updates on this developing story here on TriCities.Com.