Detectives investigating how two people became seriously ill in Salisbury continue to work with specialist health experts.
Police are now in a position to confirm that their symptoms are a result of exposure to a nerve agent. Scientific tests by Government experts have identified the specific nerve agent used which will help identify the source but at this stage in a fast-paced ongoing investigation we will not comment further.
Public safety continues to be a top priority of all agencies working together as part of this national response and we continue to liaise closely with public health and science experts.
The man in his 60s and woman in her 30s remain in a critical condition in intensive care after being exposed to the substance, now known to be a nerve agent. We are not confirming their identity.
In addition, we can also confirm that one police officer, who was part of the initial response, is also in a serious condition and receiving intensive care. Officers from Wiltshire Police are providing support to his family and colleagues.
In summary, this is being treated as a major incident involving attempted murder by the administration of a nerve agent.
We believe the two people who originally became unwell were the specific targets and are focused on identifying and finding those responsible.
Hundreds of detectives from the Counter Terrorism Policing Network have been deployed in relation to this investigation. Many hours' worth of CCTV are being reviewed as a matter of urgency and detectives are working around the clock to specifically timeline the man and woman's movements over the last few days.
We continue to appeal for witnesses and anyone with information to come forward.
To re-cap, at approximately 16:15hrs on Sunday, 4 March, the man and woman were found unconscious on a bench near The Maltings shopping centre in Salisbury.
Wiltshire Police, along with colleagues from the ambulance and fire services, attended the scene and cordons were established which remain in place.
On Tuesday, 6 March, it was confirmed that the Counter Terrorism Policing Network had taken over the lead for the investigation, due to the unusual circumstances and the specialist expertise the network can bring to the investigation.
Cordons remain in place at a number of locations.
Officers are appealing to anybody who visited Salisbury town centre and surrounding areas on Sunday afternoon and has not yet spoken to police to get in touch. They are keen to speak to anyone who visited Zizzi restaurant on Castle Street and The Bishop's Mill pub in The Maltings between 13:00hrs and 16:00hrs
Assistant Commissioner Mark Rowley, the head of Counter Terrorism Policing, said: "Having established that they were exposed to a nerve agent we are now treating this as a major incident involving an attempted murder by the administration of a nerve agent.
"Two people remain in hospital in a critical condition. A police officer who was among the first responders also remains in hospital in a serious condition and is continuing to receive intensive care. We are keeping the Chief Constable in Wiltshire regularly updated in relation to our investigation.
"Clearly people will be concerned. We continue to monitor the situation with our partners, including Public Health England. If you are feeling unwell and believe you may have been in the area where this incident happened then please seek medical advice, but we'd like to reiterate we are not seeing any evidence of a wide spread issue. We are also closely working with a range of agencies, including Public Health England to ensure public safety and wellbeing.
"We are carrying out extensive inquiries to establish exactly the circumstances behind this incident and would like to hear from anyone who has information about the incident. In particular we are keen to hear from anybody who visited the area close to the Maltings shopping centre where these two people were taken ill on Sunday afternoon, and may have seen something that could assist the investigation.
"The two people taken ill were in Salisbury centre from around 13:30hrs. Did you see anything out of the ordinary? It may be that at the time, nothing appeared out of place or untoward but with what you now know, you remember something that might be of significance. Your memory of that afternoon and your movements alone could help us with missing pieces of the investigation. The weather was poor that day so there were not as many people out and about. Every statement we can take is important."
Anyone with information should call police on 101. In emergencies always call 999.
Any members of the public who may have images or footage that could assist the investigation should send them to this address www.ukpoliceimageappeal.co.uk
Anyone with health concerns that they believe are related to this incident should either contact their GP, or ring the NHS helpline on 111 or 999, depending on the severity of the symptoms.
Temporary Chief Constable of Wiltshire Police, Kier Pritchard, said: "We continue to work with our partners, including Public Health England, the local NHS trust, local authorities and emergency services. The public will continue to see a high visible policing presence in Salisbury city to help reassure our communities."