A group of 100 children were found gathering at a former quarry at the weekend.
South Wales Police received reports that a "large group" of youths had been gathering at the former quarry near Crown Road, in Kenfig Hill.
Officers arrived at the scene at around 5pm on Saturday and they said 100 youths quickly left.
A tweet shared by officers in Bridgend read: "PCSOs Couch, Evans & Adams carried out a patrol of the old Quarry, Crown Road.
"A group of 100+ youths scarpered on seeing the police vehicle!
"Please, remind your children to adhere to COVID guidelines."
South Wales Police is reminding parents and guardians to be aware of where their children are amid the coronavirus pandemic.
A spokesman for the force said: "Shortly after 5pm on Saturday officers were called to a former quarry in Kenfig Hill following reports that a large group of youths were gathering there.
"Upon officers’ attendance the crowd rapidly dispersed.
"Parents and guardians are reminded to be aware of where their children are and what they are doing during this difficult period."
It comes as officers from South Wales Police were also called to Brombil Reservoir in Port Talbot at the weekend following reports of mass gatherings.
Key changes to lockdown rules across the UK only started on Monday.
In Wales, people from two different households can arrange to meet in parks and gardens for the first time.
However, people in Wales are being asked to stay local, which has been advised as five miles from your home.
