Update 24 March
A man in his 20s was also arrested on suspicion of possessing a firearm with intent to cause fear or violence.
He has been released on police bail while enquiries are ongoing.
The man in his 30s and woman in her 30s have been released under investigation. The man in his 50s has also been released under investigation.
Enquiries are ongoing.
Officers received reports of a man with a weapon at Linden Terrace in Gainsborough yesterday afternoon (21 March).
A cordon was put in place at the top of Linden Terrace to Trinity Street shortly after 4pm. Armed officers were deployed to the scene and a sawn off shotgun was found and recovered.
During a search of an address on Linden Terrace, officers discovered a cannabis grow inside a property and subsequently arrested a man and woman in their 30s on suspicion of the cultivation of cannabis and possession of a firearm without certificate. The man in his 30s was also arrested on suspicion of escaping from lawful custody.
A man his 50s was also arrested on suspicion of possessing an air weapon in a public place.
All three remain in police custody. Enquiries are still ongoing.
Reference: Incident 263 of 21 March.