DALLAS (AP) — Nine individuals, including seven firefighters, were hospitalized for possible carbon monoxide exposure at a Dallas condominium complex.

Firefighters were called to the complex at 1:25 a.m. Friday by a resident who said his wife was experiencing a medical emergency.

As they treated the woman, firefighters noticed the husband and one of the responding medics began to feel sick.

Firefighters examined the condo unit and picked up significant readings of carbon monoxide.

Authorities determined the carbon monoxide was the result of a vehicle in the unit's garage which had been left running for about 12 hours.

Officials say all but one of the seven firefighters has since been released from the hospital. The condition of the couple was not immediately known but they were communicating clearly after arriving at the hospital.