A woman and a baby were taken to after a liquid was allegedly thrown over them in a Lidl car park fight.
Police were called at 7.16pm on Saturday night to reports of fighting outside the supermarket in Gipton, Leeds.
A huge cordon was put in place with a heavy presence from the fire, ambulance and police services.
The scene was washed down by a police team, LeedsLive reported.
The area could be seen covered in plastic sheets and specialist equipment.
Police have rigorously tested the liquid and determined that it does not appear to be a corrosive substance.
Initial reports suggest that it may have been anti-freeze.
The woman and baby were taken to hospital as a precaution with minor injuries.
West Yorkshire Police are investigating the serious incident.
Acid attacks have increased in frequency on Britain's streets in recent years.
Earlier this month, a middle-aged man was ambushed in public toilets and sprayed with 'acid' in a vicious attack carried out by two people.
The 42-year-old victim was believed to have been sitting on the toilet when two men, dressed in dark clothing, burst in and squirted the caustic liquid over him from a clear plastic bottle.
In January, two men were rushed to hospital after being splashed with acid during a horrific attack outside King's Cross station.
