More than a dozen hospitals across the country declared major incidents as they struggled to cope after being inundated with patients.
Hospital chiefs said they resorted to the measure after some patients had to wait up to 12 hours for a bed.
The problems are affecting hospitals all over England, from the Royal Botlon in the north-west, to Addenbrookes in Cambridge and Gloucestershire and Cheltenham hospitals in the West Country.
Health Secretary Jeremy Hunt is under pressure from Labour to call an emergency summit to address what the Opposition claim is a "deteriorating" situation.
Addenbrooke's Hospital in Cambridge declared a major incident last night as it warned patients they face long waits due to "unprecedented levels of demand for our services".
The hospital said this "is putting huge pressure on the staff who are going to extraordinary lengths to care for our patients", and said the sickest would be treated first.
Royal Bolton Hospital Trust said it had been inundated with "seriously ill patients who do need to be admitted" but simply could not free beds up quickly enough to cope with this high demand.
In Staffordshire the Royal Stoke and Stafford's County Hospitals blamed a rise in elderly and vulnerable patients suffering with influenza and norovirus who need to be admitted to a hospital bed.
The full list of hospitals that have declared major incidents is as follows:
The Royal Bolton Hospital
Addenbrooke's Hospital, Cambridge
Ashford Hospital, Surrey
St Peter's Hospital, Chertsey in Surrey
Royal Stoke University Hospital
Stafford's County Hospital
Peterborough City, Cambridgeshire
Gloucestershire Royal Hospital
Cheltenham General Hospital
Walsall Manor, West Midlands
Croydon Hospital, South London
Norfolk and Norwich University Hospitals
Meanwhile, Derriford Hospital in Plymouth, The Princess Royal in Brighton, the Royal Sussex and the Bedford Hospital declared internal incidents.
One level below a major incident, this meant some operations were cancelled and staff drafted in to treat the most desperately sick.