Lincolnshire Police revealed why they cordoned off two international shops on lower Lincoln High Street on Saturday.
Officers were called to a property on the High Street near the junction with Peel Street at 10.09pm on Friday night.
They had a report that a 44-year-old man was stabbed in the arm.
His injury was not thought to be serious and he received treatment from emergency services.
A 30-year-old man was arrested later in the night and is being questioned.
To aid with the investigation, the two shops (and the flats above) were cordoned off, with scene guards still in place after midday on November 28.