A hospital is asking patients to "stay away until further notice" – even in an emergency – owing to problems with oxygen equipment.
Watford General Hospital declared a critical incident and advised people to visit other nearby hospitals as they dealt with the issue.
It added that the problem does not "pose any risk to our patients" and said pregnant women going into labour would still be admitted.
West Herts Hospitals NHS Trust said in a statement: “A small number of patients are being transferred to other hospitals in the area, with each patient being fully assessed in line with existing safety guidelines before they are moved.”
Earlier on Saturday it urged patients to seek help at nearby centres or call for advice through the 111 helpline.
West Hertfordshire Hospitals NHS Trust said the problem was resolved by 10.30pm on Saturday.
As of 5pm Thursday, 29 people had died at West Hertfordshire NHS trust hospitals after being diagnosed with Covid-19.
The trust is responsible for Watford General as well as Hemel Hampstead and St Albans City hospitals.
