A four-year-old girl was left very distressed after two schoolboys covered her in fake blood in an attack in Horsham Park.
Police said the boys threw the red liquid over the youngster whilst she was in the park on the evening of October 10.
The boys are described as white, aged 13-14, one with blond hair and one with brown. They were wearing school uniform, but it is not known from which school, officers added.
The incident took place at about 5.50pm and anyone with information is asked to report online at www.sussex.police.uk/appealresponse or call 101 quoting serial 1262 of 10/10.