CYPRESS, Texas (KTRK) -- The Harris County Sheriff's Office continues its investigation into the deaths of a mother and son in Cypress.
The Harris County Institute of Forensic Sciences identified the victims as 54-year-old Zhonglin Xin and 14-year-old Yujie Zhang.
Their exact cause of death is still undetermined, but investigators say it's believed to be from carbon monoxide poisoning. They said there gas filling the home.
Eyewitness News was told a man was checking on the family in the 13400 block of Columbia Key Drive around 10 a.m. Saturday. He called 911 around that time.
The Harris Co. Sheriff's Office tells us it appeared the two were asleep in bedrooms upstairs.
In addition, a family car was found left running in the closed garage.
The sheriff's office said there was no working carbon monoxide detector in the home.
Harris County Precinct 4 Constable deputies were the first on scene. Two deputies were overcome by the gas and were transported to the hospital, where they were treated and released.
Firefighters are urging families to add carbon monoxide detectors to their must-have lists.
"It is very dangerous. It's something that you can't just walk into your house and automatically smell like natural gas inside your house, which makes it far more dangerous," said David Padovan, with the Cy-Fair Volunteer Fire Department
Known as a silent killer, the gas is colorless, tasteless and odorless.
There are symptoms to watch out for, including headaches, light-headedness, dizziness, sleepiness, and lethargy.
If you ever believe there is carbon monoxide in your home, you should get out quickly and then call 911.