A man and teenager were attacked by a group of youths in Hassocks on Friday evening, police said.
A spokesman for Sussex Police said officers received both reports at just after 7pm.
Officers are now appealing for witnesses to both incidents.
A spokesman said: “Police received a third party report of an assault on a man in Adastra Park, Hassocks, on Friday evening (November 30).
“The informant reported that a man, believed to be in his 40s, ran from the park shortly before 7.30pm saying that he had been assaulted by a group of youths.
“A possible victim has been identified, but does not wish to take the matter further.
“At around 7.15pm, a 14-year-old suffered facial injuries requiring hospital treatment after being attacked by a number of youths.
“Anyone with information about either incident is asked to email firstname.lastname@example.org or call 101 quoting serial 1273 or 1316 of 30/11.”