DALLAS, Texas (CBSDFW.COM) — About 200 people were evacuated from a homeless shelter in Dallas after firefighters got a positive reading for carbon monoxide Sunday morning.

At 10:54 a.m. Feb. 2, Dallas Fire-Rescue responded to a medical call at The Bridge Homeless Recovery Center on Corsicana Street. While evaluating the patient they were called for, multiple tenants at the shelter approached medics complaining about a variety of symptoms, including nausea, light headedness, headaches, etc.

Suspecting a common underlying factor, firefighters retrieved their carbon monoxide detector and got a positive reading. They immediately requested multiple rescue units, EMS supervisors, HazMat and chief officers to help mitigate the situation.

A total of 16 people from the shelter were taken to local hospitals for evaluation of their symptoms. Additionally, four DFR members were taken to the hospital after being exposed to the deadly gas.

The source of the gas was isolated to the welcome building, and HazMat determined the more-than-likely source to be clothes dryers.

After shutting the gas off, HazMat ventilated the building. Officials expect that tenants will still be able to stay at the shelter as two of the three unaffected buildings can be used overnight.