Two women and four men were arrested after a man in his 50s was injured in Boultham Park on Thursday night.
People at the scene reported someone had been stabbed. Police have not yet confirmed this.
Police were called to Boultham Park just before 7.30pm on Thursday, July 4 after receiving reports of an altercation between a number of people.
The police investigation is ongoing this morning.
The victim’s injuries are not believed to be serious, police said.
As previously reported, a police cordon was put in place from around 8pm with a forensics team turning up to examine the area later in the evening.
A spokesperson for Lincolnshire Police said: “Officers attended and two women, both aged 30, and four men, all aged between 22 and 45, were arrested on suspicion of GBH. They remain in custody for questioning at this time.
“Investigating officers are pursuing a number of lines of enquiry, including if any weapons were used during the incident.”
A reporter at the scene witnessed a man trying to climb over a fence in line with the police cordon before leaving the scene.
Any witnesses or anyone with information in relation to this incident should contact police on 101 or via email at [email protected] quoting incident 392 of July 4.
It can also be reported through the independent charity Crimestoppers anonymously on 0800 555 111 or online here.