The wife of an off-duty Detroit police sergeant has been shot to death outside a pharmacy.

Police spokesman James Tate says 47-year-old Rose Cobb had been shot at least once in the head. She was dead at the scene.

Tate says her husband was inside the east side CVS about 9 p.m. Wednesday when shots were heard.

Cobb had been shot through the vehicle's window and nothing appeared to be taken. The shooter is believed to have left on foot.

Tate says the motive for the slaying is under investigation after police earlier reported it as an apparent carjacking.

Tate says people were in the parking lot at the time of the shooting, but may have driven away in fear for their own safety.