Two men, in their 20s, were sent to a hospital after being stabbed.
The men's injuries are not believed to be life-threatening.
The incident occurred in Catherine Street, near the junction with St Peters Street, at around 2.40am yesterday.
Detectives investigating the assault in St Albans City Centre are appealing for witnesses and information.
Detective Constable Claire Mann, from the St Albans Local Crime Unit, said: “Thankfully the men were not more seriously injured during the incident.
“We are currently working to establish the circumstances around what happened and trace those involved.
“I am appealing for anyone who saw the incident, or events leading up it, to please get in contact.”
Anyone with information should contact DC Mann via email to claire.mann@herts.pnn.police.uk or by calling the non-emergency number 101, quoting crime reference 41/28885/18. You can also report information online at www.herts.police.uk/Report.
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