Cronauer said firefighters saw thick black smoke when they arrived.
The fabric of the upholstered chair in the living room had burned but was not on fire, Cronauer said.
"When firefighters arrived, they didn't see the chair burning," he said.
Cronauer said the fire did not have enough oxygen to spread. When firefighters moved the chair outside, it burst into flames, he said.
Hoover's husband and son had left the house about 30 minutes earlier to go to the market, Cronauer said. When they returned they saw smoke and heard alarms.
Cronauer said smoking-related fires are the leading cause of fatal fires in Maryland. He said cigarette ashes, which can reach temperatures of 500 degrees, can spark a fire on furniture before a victim realizes there is fire.
"It'll ignite anything," he said.
Cronauer said smoke increases the concentration of poisonous carbon dioxide in the air, causing confusion and unconsciousness. He said it is possible Hoover heard the smoke detectors and then stood to get out of the house.
But smoke can quickly overcome a person, he said.
While the number of fire deaths in Maryland has declined in recent years, smoking remains the leading cause of those deaths. In 1996, nearly 20 percent of the state's 61 fire fatalities were caused by smoking-related blazes, Cronauer said.
About 25 firefighters from Maugansville and Long Meadow responded to the incident.