Police in St. Petersburg, Fla. said Monday that a teenage couple died of carbon monoxide poisoning while sitting inside an SUV in a locked garage. 

Authorities said the mother of 17-year-old Dorian Gomez Poehlmann found the bodies of her son and his girlfriend, 14-year-old Emily Sabow, early Monday. Investigators say the deaths don't appear to be suicides, though they did not specify what led them to that conclusion.

"It appears that this was a horrible tragedy that has clearly devastated both of these families," said Assistant Chief Jim Previtera.

Police said Poehlmann left his mother's home Sunday afternoon to pick up Sabow in the family's 2002 Mitsubishi SUV. Unbeknownst to Poehlmann's mother, her son later returned with his girlfriend to the detatched garage. At some point, the door closed, trapping the teens inside the unventilated building. 

After calling her son's cell phone with no response, Poehlmann's mother reported the teens missing at approximately 11 p.m. local time Sunday.

Both teens' families tried to access the garage early in their search, but were unable to pry the door open.

"Because of a garage door opener, they couldn't get the door up but they didn't believe the kids were there," Previtera told Fox 13. 

Early Monday, information from Poehlmann's iPhone led the families back to the garage, where they were able to open the door using kitchen tools and found the teens' bodies in the car. 

The St. Petersburg Times reported that Poehlmann's body was slumped out of the SUV as if he had tried to get out. The car key was in the on position. Fox 13 reported that the SUV was out of gas. 

Investigators were trying to determine why the garage door closed with the SUV still inside. 

Click for more from Fox 13 News.