DALLAS (CBSDFW.COM) – A couple who left a car running in their garage for approximately 12 hours suffered from exposure to carbon monoxide and so did seven firefighters who responded around 1:25 a.m. Friday.

It happened at a condominium complex in the 4200 block of Holland Avenue.

carbon monoxide exposure in Dallas (CBS11)

A man called 911 after waking up to his wife experiencing a medical emergency.

As medics evaluated the patient, they began to suspect something else was going on when the husband, as well as one of the medics, “began feeling symptomatic,” Dallas Fire-Rescue said in a news release.

It was at that point when an engine company checked the unit and picked up significant readings of carbon monoxide.

The woman and her husband and seven firefighters were taken to the hospital to be evaluated for exposure to the often deadly gas.

“In speaking with the couple, it was determined that the CO was the result of a vehicle, in their garage, which had been left running for approximately 12 hours,” Dallas Fire-Rescue said.

Hazardous materials technicians responded to the scene for a more thorough check of the entire complex, but noted significant dissipation in the unit of origin by the time they arrived.

Though residents were evacuated from the remaining units, it was only for a short time, as HazMat determined there was no danger to them.

As of late Friday morning, all but one firefighter, one of the first arriving medics, had been discharged from the hospital.