Hialeah Fire Capt. Cesar Espinosa said a passerby spotted the two in the car parked outside Hialeah City Hall on Wednesday morning.
The Miami Herald reports the woman was dead. The man was taken to the hospital for what Espinosa called “his altered mental status.”
Authorities said it’s unclear whether the two had a relationship and were still investigating how the woman was killed, but they believe she was stabbed or shot.
Their names haven’t been released.
No further details were immediately available.