Emergency services, including police, fire and rescue services and ambulance crews were on the scene as they attended a ‘medical incident’ at HMP Lewes, which was reported at approximately 12.30pm.
The Prison Service confirmed that three inmates and three staff members were taken to hospital.
A further 10 or 11 people have been treated, with food poisoning or deliberately-contaminated food being considered as possible causes.
Signs had read that the hospital was closed due to a ‘major incident’ and a decontamination tent was set up outside Eastbourne District General Hospital.
East Sussex Healthcare NHS Trust confirmed that the signs had since been taken down.
A spokesperson said: “Earlier today, Eastbourne District General Hospital was stood up to potentially receive casualties following an incident at HMP Lewes.
"We have now been stood down. Care at the hospital has not been affected, and continues to operate as usual”.
A CBRN (Chemical, Biological, Radiological and Nuclear) incident support unit was seen at the prison in Lewes.
A spokesperson for East Sussex Fire and Rescue said: "The fire service were called to assist ambulance at an incident at HMP Lewes and are currently working with other agencies and specialist teams."
A spokesperson for South East Coast Ambulance added: "We are in attendance at a medical incident at HMP Lewes."
Sussex Police also confirmed that they were in attendance at the prison in Lewes assisting the ambulance service.
A spokesperson said: “Sussex Police are assisting the ambulance service following the report of a medical incident at HMP Lewes at around 12.30pm on Thursday (March 28).
Lewes MP Maria Caulfield also expressed her concerns following the incident.
She tweeted: "Concerned to hear about the incident at Lewes prison. Emergency services are on scene and it is important to let them deal with the situation in looking after those affected."
1. ‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison
‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison Photo: Sussex News and Pictures
2. ‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison
‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison Photo: Sussex News and Pictures
3. ‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison
‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison Photo: Sussex News and Pictures
4. ‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison
‘Major incident’ closes Eastbourne A&E as emergency services attend ‘medical incident’ at Lewes prison Photo: Sussex News and Pictures