Paramedics attending an emergency callout had an abusive note left on their ambulance telling them "you can't block people's driveways".
The East of England Ambulance Service said the note was placed on a vehicle in Southend on Thursday night.
The message said the crew should have "asked" before parking and "come out when we beep the horn for 10 minutes".
The ambulance service said those who abuse paramedic crews should "remember they are there to save lives".
A spokeswoman for the ambulance service said: "Our crews are instructed to be considerate where they park.
"However, in areas where parking is limited, an ambulance may need to park in the first available space to attend a critically ill or injured patient."
Earlier this year the same service received another abusive message branding a paramedic a "blind idiot".
It was left a rapid response vehicle's windscreen outside an emergency in Luton in August.
The ambulance service said: "No-one deserves to be abused for doing their job, so if a marked ambulance is parked across your drive for a few minutes, please think - is your parking space more important than a neighbour's life?"
This latest note was posted on the Your Southend Facebook group.
The post has had dozens of supportive messages for the emergency service, branding the writer of the note as a "disrespectful uneducated fool" and said they had "no consideration".