A grandfather and his granddaughter were threatened by a gang of youths with one of them saying he was going to "stab and spit" on them.
Peter Cotterell, 58, from Caerphilly, was out with his 11-year-old granddaughter to walk his dogs for their once-a-day exercise.
When he got to the park Mr Cotterell said he saw five young men hanging around and told them to leave as they were breaching government guidelines concerning coronavirus.
Mr Cotterell said: "One of them went absolutely berserk on me and he started swearing. What he was coming out with was vile.
"He threatened to stab me and he threatened to spit on me and said: 'Your f****** family are going to die'. He was deranged.
"My granddaughter was terrified. She was screaming and crying and that's I had to leave because I didn't want her to be upset.
"I don't know what is wrong with kids these days. It was absolutely crazy."
A spokesman from Gwent Police said an 18-year-old man had received a police caution as a result of the incident.
He added: "We received a report of man making abusive and verbal threats to others in Llwyn-On Street, Energlyn, Caerphilly at around 2.20pm on Tuesday, March 31.
"Officers arrested an 18-year-old man from the Caerphilly on suspicion of committing a section four public order offence on Wednesday, April 1.
"He has received a caution in relation to this incident."
