A hospital has declared a critical incident due to its casualty department being extremely busy and bed shortages.
James Paget University Hospital, in Gorleston, near Great Yarmouth, announced the situation late on Monday.
NHS trusts declare critical incidents when they face extraordinary pressures and need to prioritise certain care services.
In a statement, it said people should only attend its A&E department in a "genuine emergency".
The James Paget University Hospitals NHS Foundation Trust said it had made the alert "due to an increased number of attendances at our emergency department and pressure on our bed capacity".
"We are currently experiencing high demand at our hospital," a statement added.
"We are working closely with our partners in the Norfolk and Waveney healthcare system to maximise capacity during this period of high demand."
The hospital cares for 250,000 residents across the Great Yarmouth, Lowestoft and Waveney areas.
It urged any patients needing urgent - but not emergency - care to call or visit NHS 111 for advice, while those with less urgent concerns should contact their GP or pharmacist.
Patients with appointments or booked in for procedures have been advised to visit the hospital as planned, unless they have been contacted.
The NHS Norfolk and Waveney Integrated Care Board - which oversees the James Paget, Norfolk and Norwich University and King's Lynn's Queen Elizabeth hospitals - said the system was "extremely busy".
"We are working hard to improve how patients flow through our hospitals and are discharged once they have received their treatment," the board said in a statement.
"We would ask anyone who has a family member in hospital who is ready to be discharged to speak with staff around how they might be able to provide support, such as transport, to help them continue their recovery at home."
However, it said anyone who felt unwell should not delay in going to hospital or seeking help from the NHS.