A hospital has closed after declaring a "critical incident" and has asked people to stay away even in an emergency.
Watford General Hospital has shut because of an "issue relating to the hospital's oxygen equipment" - but has confirmed that it remains safe for its current patients.
It also confirmed it has not run out of oxygen despite reports suggesting this.
The hospital is closed to all patients except women in labour - and it has been confirmed that a number of patients have been transferred to other hospitals.
West Hertfordshire Hospitals NHS Trust put a message out on its social media channels this morning warning everyone to stay away from A&E.
It reads: "Please DO NOT attend Watford General’s emergency department until further notice, even in an emergency.
"Go to your next nearest hospital with an emergency department. Anyone with non-urgent issues should seek advice via https://111.nhs.uk."
It added in a further tweet: "Sat 4 April: Our critical incident remains in place and ALL PATIENTS MUST STAY AWAY from Watford Gen Hospital except for women attending our delivery suite. We have NOT run out of oxygen and our patients are safe."
An official statement from the NHS trust says: “As a result of a technical issue with our individual hospital’s oxygen equipment, which does not pose any risk to our patients, West Herts Hospitals NHS Trust declared a critical incident on Saturday April 4 and has asked that people do not attend Watford General Hospital.
“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.”
The critical incident remains live and the situation is currently being assessed by technicians, Watford Observer reports.
Following the government's advice for people to stay at home and avoid going out unless absolutely necessary, no visitors are allowed at West Hertfordshire Hospitals - with exceptions for maternity and paediatrics.
Several hospitals around the country have introduced stricter measures to help fight the spread of Covid-19.
