On Sunday, online videos emerged showing two people who appear to be mortuary workers placing the body bag into a vehicle.
The workers are later seen pulling the bag open, and one can be heard saying the patient is still alive.
The incident has sparked widespread anger on Chinese social media.
Officials in the Shanghai district of Putuo confirmed the incident late on Monday, adding that the patient had since been taken to hospital and was in a stable condition.
District authorities said five officials and one doctor were under investigation.
