DC Becky Fowler, of Louth CID, is appealing for witnesses to an incident that took place in Mablethorpe earlier this month.
Shortly before midnight on Tuesday August 4, an altercation occurred at a chalet park in Lincs Close.
During the incident, a 36-year-old man from Nottingham was assaulted and suffered a broken leg.
Three male youths from Rutland (age 16 and 17), and a 31-year-old man from Hull, were arrested on suspicion of affray and GBH offences and later bailed to a date in November.
DC Fowler is keen to trace any further witnesses to the incident, in particular anyone who has mobile phone footage.
Anyone with information should contact DC Fowler by dialling 101 and quoting the incident number.
Report crimes anonymously by contacting Crimestoppers on 0800 555 111.