A decontamination team was called to Doncaster after chemicals were thrown through a car window at traffic lights.
The team was rushed to Doncaster Royal Infirmary, after two men were injured inside the vehicle when the substances were thrown at them through the open window.
The incident took place just before 2.30am in the early hours of Thursday, after which point the two men drove to Doncaster Royal Infirmary for treatment.
A decontamination team was called into action, while work was carried out to establish which chemicals had been used in the attack.
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 is thought the substance was alkaline in nature.’’
A spokesman for Doncaster and Bassetlaw Hospitals Trust said the team, which includes police officers and firefighters, were sent to the hospital after two men arrived at the hospital at around 2am claiming ‘unknown chemicals’ had been thrown at them.
He 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.
“A&E remained open throughout the contamination process, and remains open today.”