Five people have been treated after an apparent acid attack which also left several cars damaged.
Armed police and paramedics arrived at the Burghley Drive playing fields in Corby, Northamptonshire, at around 6.30pm on Wednesday after young people on mopeds were spotted throwing a liquid substance over vehicles.
Parents and their children were in the park for football practice with Hellenic Fisher FC, the Northamptonshire Telegraph reported.
A group of four motorbikes drove onto the field while football games were being played. They performed wheelies before driving off on a footpath, Northamptonshire Police said.
Two people in dark clothing and face coverings rode into the car park of the recreation ground before squirting a noxious substance on multiple cars, causing criminal damage to three of them.
Five people were reportedly treated by medics after attempting to clean the liquid off the cars to help drivers, before realising it had an acidic smell.
They were decontaminated at the scene by East Midlands Ambulance Service as a precaution, but none of them sustained injuries.
Authorities believe the substance was a type of solvent or hydrochloric acid, but will carry out further tests to confirm today.
Police are now searching for the driver and passenger of a red moped believed to be involved in the incident, and have appealed for witnesses to come forward.
Chief inspector Paul Cash, head of local policing for Corby and Kettering, described it as an “act of mindless criminal damage”.
He said: “We appreciate that incidents of this nature are hugely concerning to those involved and the local community, and I want to reassure everyone that we are taking this incident seriously.
“The Corby Neighbourhood Policing Team are leading the investigation and as part on their enquiries to establish who is responsible for this act of mindless criminal damage, they will be out and about talking to members of the local community.
“We’ve been working hard to tackle the ongoing issues of illegal motorcycles in Corby. We have had some good results over the past two years and continue to put people in front of the courts.
“However, there is no room for complacency. There’s still a lot more work to be done, which is why we need the public’s continued support to tackle this as they are the eyes and ears of our communities.
“We would also encourage anyone who lives or works in the town to report any suspicious activity involving motorcycles to help us identify those responsible for not only causing misery to others but putting lives at risk because of their irresponsible behaviour.
“Anyone with concerns, whether connected to this incident or motorcycle-related anti-social behaviour in general, is encouraged to speak to the neighbourhood team as they will be happy to help.”
Corby police sergeant Keely Cox said on Wednesday night that police “do not believe this was a targeted attack”.