Police seized three machetes and a knife after a man was stabbed in a street fight between two groups of men in Preston.
Officers say the incident is believed to have happened between 8.30pm and 9pm on Saturday in Fitzgerald Street, Ribbleton.
A local man in his twenties was taken to the Royal Preston Hospital with wounds to his lower back and buttocks.
His injuries are not thought to be life threatening and he remains in hospital for treatment.
A 25-year-old man was arrested on suspicion of affray, possession of an offensive weapon and possession of cannabis. He has been bailed until July 1 pending further enquiries.
Following the incident officers recovered three machetes, a knife and a balaclava from underneath a parked car on a nearby street.
A sheath, which is thought to be for a large sword or machete type knife, was also recovered.
DI Philip Bowerbank said: “This is an extremely serious incident and we have a team of dedicated officers investigating the circumstances around the attack and piecing together the events that led up to this happening.
“We also have extra patrols in the area and I would urge anyone who is concerned or who has information about this attack to get in touch with us as soon as possible on 101.
“We are looking into various lines of enquiry and officers are conducting CCTV and door-to-door enquiries.
“We believe that the men involved in this altercation were known to each other and it is fortunate the victim’s injuries were not more serious.
“The effects of knife crime can be devastating and I would encourage those involved in this brutality to think before they get involved and potentially find themselves behind bars.
“We do not and will not tolerate this sort of crime in Preston or across the county and we are determined to find those responsible.”