Seven people have been arrested over a spate of nitrous oxide thefts after an attempted raid on an NHS hospital, police said.
A woman and six men, all from Norwich in Norfolk, were held after Cannock Chase Hospital was targeted in the early hours of Friday, Staffordshire Police said.
It followed a spate of thefts of nitrous oxide - which is also known as laughing gas or hippy crack - from medical sites in the county.
The drug, used medically as a painkiller and anaesthetic, has become a popular recreational drug.
Police said the seven - a woman aged 47 and men aged between 20 and 39 - were arrested when officers swooped on three cars in Winson Green in Birmingham.
Chief Inspector Sarah Wainwright said: "These arrests are a result of shared intelligence and collaborative working between Staffordshire Police and our colleagues at West Midlands Police, Norfolk Constabulary and the Central Motorway Police Group."
The attempted burglary at the hospital took place at around 1.30am on Friday.
It followed the theft of two oxygen cylinders from Stafford County Hospital at a similar time on April 4, after thieves gained entry to a store room, police revealed earlier this week.
Earlier on April 4, at 12.30am, there was an attempted burglary at Cannock Chase when a man got into an outbuilding.
Prior to that, in the early hours of March 31, Cannock Chase had again been the target as three men in dark clothing forced their way into a store room and took 13 bottles of nitrous oxide before making off in a silver Peugeot 307.