The ferry carries passengers and cars between Port Said and Port Fouad.
The ferry's captain told motorists who were boarding the ferry to make space for an ambulance, which was carrying a patient in critical condition, the state-run MENA news agency reported Sunday.
The driver of the car then attempted to move the vehicle, which crashed through the front gate of the ferry and fell into the canal.
A rescue team retrieved the vehicle, but was unable to save the family inside.
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