Armed police officers descended on the Portland Street area in Lincoln at the weekend in response to reports of several men with weapons.
Three men were arrested, two in their 30s and one in his 40s, when officers rushed to the scene.
Residents described the arrival of between five and six police vehicles, dog handlers and armed officers after 2.15pm of Saturday, February 10.
Underwater search teams were also seen in the Sincil Drain area and a section of the road and path was cordoned off.
Divers were searching for any possible discarded weapons.
A Lincolnshire Police spokesperson told The Lincolnite the investigation is still ongoing.
No charges have been made at the time of publishing.
Anyone with information relating to the incident is being asked to contact Lincolnshire Police on 101 quoting incident number 237 of February 10.