A decontamination team has been called out to a Doncaster hospital, after two men were injured when a chemical substance was thrown at them through an open car window as it waited at traffic lights.
The incident took place just before 2.30am this morning, after which point the two men travelled to Doncaster Royal Infirmary for treatment.
A decontamination team were called into action, while work was carried out to establish which chemicals had been used in the attack.
A spokesman for Doncaster and Bassetlaw Hospitals Trust said: "The men said they had chemicals thrown at them in a car when they were off-site.
"Because the type of chemicals thrown at them was not known at that point, normal decontamination procedures had to be followed which included calling emergency services to the site.
"The two men would have been decontaminated in a tent located outside the hospital, and staff would have put on special suits - which would have looked like hazmat suits.
"The car the men arrived in, and where the chemicals were thrown at them, would also have to have been decontaminated.
"The primary doors to the department were closed and the secondary doors in outpatients were used for a short time while the decontamination process was carried out.
"The chemicals used in the attack were found to be ammonia. The men were treated and discharged, and the incident is now with the police.
"Members of the public would have been told that there was a chemical incident.
"A&E remained open throughout the contamination process, and remains open today."
A South Yorkshire Police spokesman said: "Two men, who attended Doncaster Royal Infirmary to receive treatment for their injuries, were waiting in their car at a set of traffic lights, when they had a chemical substance thrown at them through the open window.
"Accident and emergency was cordoned off at the hospital to prevent contamination but was later reopened.
"Both of the men will not suffer any long term medical issues from the attack as it thought the substance was alkaline in nature.
"Police are continuing with their investigation.
James Milne, 18, who visited the A&E department with his unwell girlfriend Hayley Wilde, 23, last night claims he heard an 'explosion' just outside A&E at around 1am.
James, of Intake, said: "I heard this big explosion and all the staff and patients in A&E went to have a look at what had happened but security said they weren't allowed to until they found out what had happened.
"A&E was cordoned off and we weren't allowed outside for ages. Later staff said there had been a chemical explosion outside.
"Two sections of the car park were cordoned off for ages after it had happened.
"My girlfriend's in there with suspected meningitis and it's worrying because they haven't really explained what the chemical explosion was caused by."
The spokesman for DBH said no reports of an explosion within the hospital grounds have been received.
South Yorkshire Fire and Rescue have been contacted for more information.