Essex Police said two teenage boys and a man were taken to hospital after being stabbed in Colchester between 18:22 and 18:31 GMT on Saturday.
As a result, the force's temporary deputy chief constable approved use of additional powers to search people.
The "robust policing tactic" was used for three hours to "ensure order had been fully restored", the force said.
A 17-year-old boy and an 18-year-old man from London were arrested, along with a 21-year-old man from Barking.
Ch Insp Simon Anslow said none of those who were stabbed suffered life-threatening injuries.
"This is a rare situation in any town and we are using the full range of legal tools at our disposal to keep the overwhelming majority of people safe, while making sure those intent on causing trouble will be swiftly picked up and dealt with," he said.
"We will be pursuing a vigorous investigation to put all those we can find who are responsible for this detestable behaviour before the courts."
The use of section 60 of the Criminal Justice and Public Order Act 1994 gives officers the power to search people for dangerous objects and weapons without the need to have a reasonable suspicion.
The powers were in force in Colchester town centre from 18:40 until 21:50 GMT on Saturday.
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Colchester MP Will Quince said he supported the force's use of the powers in this instance.
"Their swift action in getting the section 60 order, which is a rarely used piece of legislation, means they can stop anybody without reasonable cause to check if they have a weapon within a certain time frame - I applaud the police for doing that," he said.

A blogger posted screenshots suggesting a Carmarthenshire councillor shared a Facebook post by a far-right group.
The post said: "When a dog attacks a child it is put down. Shouldn't we do the same with sex predators?"
Tegwen Devichand said she did not remember sharing the post and opposed the death penalty.
Ms Devichand, who is Labour deputy group leader at Carmarthenshire council, said: "I couldn't put a horse down, let alone a human being."
The post which Ms Devichand appears to have shared was initially posted by far-right group Britain First.
Ms Devichand opposes plans to remove English-stream education at Ysgol Llangennech which were approved by Carmarthenshire council in January.
"People should have choice, it shouldn't be forced on them," she said.
The decision has been controversial with one Labour councillor Kim Thomas describing it as "segregation... at worst, apartheid".
The decision has been controversial with one Labour councillor Kim Thomas describing it as "segregation... at worst, apartheid".
Plaid Cymru has accused Labour members of working with UKIP to undermine the council's decision.
She also said Labour had not contacted her about the matter and she had not been told the party was investigating.
Ms Devichand said she was complaining to the police about a "hate campaign" against her.
On Sunday Labour said a different member connected to the row had been suspended.
Plaid Cymru Carmarthen East and Dinefwr MP Jonathan Edwards said over the course of the weekend "we have seen Labour members and an elected councillor exposed for sharing the propaganda of ultra-right groups.
"This is in addition to another elected councillor branding Labour's own education policy as 'apartheid'."
"Launching an investigation into the Llanelli Labour party is a welcome first step, but the party's head office must take swift and immediate action to stamp this out this type of divisive campaigning."
A Welsh Labour spokeswoman said: "The Labour Party takes all complaints of this nature very seriously. The local party in Llanelli have made us aware of complaints and an investigation is under way."
Police invoked special stop and search powers after three people were stabbed within 10 minutes in a town centre.
[NEXT_CONCEPT]
Labour has launched an probe into complaints about members connected to a row over the move to change a primary school to Welsh-medium education.