A spokeswoman said the council was ‘shocked and saddened’ to hear of the attack, which happened last night around 8.45pm.
She added: “Whilst incidents such as these are disturbing to our local people we would like to offer the reassurance that this is being treated by Sussex Police as an isolated incident and our District overall has some of the lowest levels of criminal behaviour in the country.”
Large amounts of litter were left in the park after people flocked to the area amid record March temperatures.
This morning, March 31, park rangers were left facing a major clean up operation with a number of residents mucking in to pick up the rubbish.
The council spokeswoman said: “Litter has become an increasing problem in public spaces during the lockdown, most notably in and around parks and countryside sites, which are seeing a higher volume of visitors than usual.
“With the lockdown easing and summer on its way, the Council is calling for co-operation to help reduce littering and fly-tipping across the District.
“Please show respect for the environment when using public spaces by disposing of waste responsibly especially during the coronavirus pandemic.”
The Council is set to increase the number of bins in Horsham Park but it urged people to take their rubbish home if bins are full.
The spokeswoman said: “We should all have pride in our natural environment, particularly as more of us are now enjoying walks in outdoor areas.
“Please note that in line with Government guidelines, if you do decide to meet up to enjoy the outdoors you must meet in groups of up to six people maximum or two households, socially distance and wear face masks where appropriate.”