Officers received reports of an incident at Great Western Hospital in the early hours of Wednesday, July 22.
Two vehicles had entered the grounds towards the energy centre and police say four people wearing balaclavas and carrying crow bars were spotted exiting the vehicles.
When officers arrived at the scene, they discovered the vehicles had left, but response officers, specialist ops and colleagues from Gloucestershire Constabulary worked with Wiltshire Police to locate the vehicles, which were stopped on the A417.
Four people from London and Gloucestershire – aged 22, 27, 29 and 31 – were arrested on suspicion of attempted burglary.
Police believe the suspects were targeting nitrous oxide canisters, but their enquiries are still ongoing.
The 29-year-old was also arrested on suspicion of drug driving, while the 27-year-old was arrested on suspicion of drug driving and possession of an offensive weapon.
They remain in custody for questioning.
Chief Insp Carly Nesbitt said: “This was excellent teamwork by all involved to make these four arrests and prevent a burglary taking place at the hospital. It is believed the suspects were targeting nitrous oxide canisters – enquiries are currently ongoing.
“Anyone with information should call 101 and quote crime reference number 54260088257.
“Alternatively, call CrimeStoppers anonymously on 0800 555 111.”
A spokesperson for Great Western Hospitals NHS Foundation Trust said: “We are supporting Wiltshire Police with their enquiries.”
