A hospital has declared a critical incident due to its casualty department being extremely busy and bed shortages.
James Paget University Hospital in Gorleston, Norfolk, declared the incident on Monday.
NHS trusts do this when they face extraordinary pressures and need to prioritise certain care services.
In a statement, the hospital, near Great Yarmouth, said people should only attend its A&E department in a "genuine emergency".
In a message to staff on Monday, seen by the BBC, the hospital said it had 78 patients in escalation bed areas.
Escalation beds are used by hospitals to provide extra capacity for limited periods.
In the same message, the hospital said: "The health and care system in Norfolk and Waveney is also experiencing extremely high levels of demand."
A hospital spokesman said: "We are currently experiencing high demand at our hospital and, as such, would remind people to only attend Accident and Emergency if it is a genuine emergency.
"When needing urgent medical care but it's not an emergency, visit NHS 111 online or call NHS 111 for advice on how to get care at any time of day or night. For non-urgent cases, speak to your GP practice or a pharmacist.
"Patients with appointments/procedures at the hospital should still attend as planned, unless they hear from us.
"We are working closely with our partners in the Norfolk and Waveney healthcare system to maximise capacity during this period of high demand."
NHS Norfolk and Waveney Integrated Care Board (ICB) confirmed demand for services across the health and care system in the area was "very high".
An ICB spokeswoman said: "This is coupled with the presence of highly infectious conditions such as norovirus, flu and Covid-19.
"One of our key focuses is to improve the way patients flow through our hospitals and are discharged after treatment to continue their recovery out of hospital," she added.
The ICB said community bed capacity had been increased, extra at home support was being provided, and hospitals are using GPs to helps assess patients who do not need hospital treatment.
People with relatives in hospital are being asked to discuss with staff ways to help streamline the discharge process, when patients are ready to go home.