Aurora, CO – Several people were hospitalized Thursday night after being exposed to elevated levels of carbon monoxide in an Aurora apartment complex, according to officials with Aurora Fire Rescue.

Aurora firefighters and workers with Xcel Energy responded to 15600 E. Iliff Place at approximately 7 p.m. Sept. 24 to ventilate several units that reported high levels of the noxious gas.

A total of three people were eventually taken to a local hospital for treatment. No information on their conditions was available Friday morning, according to spokesperson for Aurora Fire.

One dog was also rescued from a unit with high carbon monoxide levels. The animal was left in the custody of a neighbor whose unit was not affected by the gas.

Residents were able to return to their homes after officials ventilated the complex and confirmed stable levels of carbon monoxide in 10 different units.

Investigators believe the gas emanated from mechanical equipment that was operating in the area earlier in the day, fire officials said.