Baltimore, MD- The state medical examiner’s office says a couple found Tuesday morning in their Northeast Baltimore home died of carbon monoxide intoxication.

A spokeswoman said the deaths of Tony Thomas, 52, and Carol Thomas, who was in her early 50s, appear to have been an accident. However, authorities are investigating what happened.

Fire Department spokesman Kevin Cartwright said investigators, who used electronic monitoring equipment to measure air quality and checked appliances for possible leaks, initially found evidence of oxygen depletion in the home but no evidence of carbon monoxide, or any other gases.

Linda Foy, a spokeswoman for Baltimore Gas and Electric, said the utility returned to the home yesterday and checked the dryer, stove and hot water heater and found “no levels of carbon monoxide.” The utility investigators could not check the furnace because it was “inoperable,” but Foy declined to speculate on what that might indicate.

The police investigation remains open, said spokesman Troy Harris.

Authorities said a neighbor called police when he was unable to reach any of the residents in the home. Police arrived about 8 a.m. and found Carol and Tony Thomas dead at the scene. The couple’s 17-year-old daughter, Anita Thomas, and her 1-year-old son were semiconscious when they were taken to Maryland Shock Trauma Center and University of Maryland Medical Center,

respectively, where they were treated and released.