A “popular” NHS nursing assistant who was treating coronavirus patients at Watford General Hospital has died.

John Alagos, 23, from Watford, fell ill during a 12-hour shift at Watford General Hospital on Friday but did not leave work early, the Mail on Sunday reported.

His mother, Gina Gustilo, 50, told the newspaper he complained of suffering a headache and high temperature throughout his night shift.

Ms Gustilo later found her son unconscious in his bedroom after he returned home from his shift.

The cause of Mr Alagos' death is unknown, however Ms Gustilo told the BBC that the family are waiting to hear if he had tested positive for Covid-19.

She told The Mail on Sunday: “I asked 'Why didn’t you come home?’ and he said he had asked other staff but they said they were short of staff and they did not let him go.

"I said, ‘OK, take some paracetamol.’ After a few minutes, I found him turning blue in his bed.”

Ms Gustilo immediately called 999 after finding her son unconscious in his bedroom.

However, paramedics were unable to resuscitate him.

Ms Gustilo told the newspaper that colleagues of her son told her he was not wearing right protective clothing.

She continued: “‘They wear PPE, but not totally protective of the mouth. They wear the normal masks.”

Ms Gustilo said her son did not have any underlying medical conditions.

Tracey Carter, chief nurse at West Hertfordshire Hospitals NHS trust, described Mr Alagos as “very popular” and that he “will be missed greatly”.

She said: “Our staff are fully briefed on the symptoms of Covid-19 and we would never expect anyone to remain at work if they were showing these symptoms or indeed were unwell in any way.

“We have always kept our staff updated on the latest PPE guidance to make sure they have the right level of protection for where they are working. John was very popular and will be missed greatly by his colleagues."

However, the trust says it "cannot comment further on the cause of death at this stage".

Meanwhile, a critical incident at Watford General Hospital has been stood down.

A critical incident was declared yesterday morning (Saturday) after a "technical issue with the hospital's oxygen equipment".

The entire hospital was shut to new patients except the maternity unit and people were told to go they would need to find alternative emergency care at another hospital.

However, West Hertfordshire Hospitals NHS Trust, which runs the hospital, stood down the critical incident at 10.30pm on Saturday night.

The trust said: "West Hertfordshire Hospitals NHS Trust stood down its critical incident tonight (Saturday) at 22.30.

"This means that patients can attend Watford General Hospital as usual and that ambulances can bring patients to Watford General instead of to neighbouring hospitals.

"The issues experienced today have been resolved and a safe level of oxygen was maintained throughout the duration of the incident."