At least six people were involved in a late-night fight in Borehamwood town centre.
Police say it happened between 11.30pm and 11.50pm on Tuesday November 16 in Shenley Road.
It was reported a group of at least six were involved in a verbal altercation which then turned physical.
Police have been investigating the affray with three people arrested in connection with the incident.
The men, aged 25, 27, and 29, have been released under investigation while enquiries continue.
As part of Hertfordshire Constabulary's enquiries into what happened, officers are appealing for witnesses and information.
Investigator Kay Leverton, from the Hertsmere local crime unit, said: "Our enquiries are continuing at this time to establish the circumstances around what happened.
"As part of the investigation, we are appealing for anyone who saw the incident, or events leading up to it, to please get in touch. Any information at all could assist us moving forward."
Anyone with information is asked to email kay.leverton@herts.police.uk, report information online at herts.police.uk/report, or call 101, quoting crime reference 41/89960/21.
Or contact Crimestoppers anonymously on 0800 555 111 or via crimestoppers-uk.org.
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