An autopsy is expected to soon confirm how the 35-year-old man died.
The car erupted in flames just before paramedics arrived.
Police were on the scene of a wooded area on Detroit’s west side.
Investigators said the victims were stabbed before someone set fire to the house.
The 54-year-old shooter told police he “accidentally” shot McBride, who is 5 foot 4, in the face with a shotgun because he thought she was an intruder.
Renisha McBride, 19, was in a car crash and seeking help when she knocked on the man’s door at 2:30 a.m. last week.