"It is a very active investigation," police spokeswoman Louise Rogers-Feher said Thursday.
A summary of the corresponding police report states that a thief stole a Porsche Cayenne, Maryland tag number 584M126, was stolen from the house in the 7000 block of Bellona Avenue before the blaze was started. A television and DVD player were also missing.
County emergency officials said Monday that units arrived at the house at around 8:18 a.m. Monday, and at 8:30 a.m., a firefighter fell through the first floor into the basement while entering the house.
The firefighter, who officials said was from the Hillendale station, was able to escape the building through a basement door and was not injured.
Police said Friday that an accelerant was used to start the fire, and that it was set in two locations in the house.
Rogers-Feher asked anyone with information on the incident to call the Baltimore County Fire Department's arson unit at 410-887-4870.