Detectives are appealing for witnesses and information as part of an ongoing investigation in Borehamwood.
At around 5.10am on Thursday 9 November, police were contacted to report that attempts were being made to force entry to a property in Gateshead Road.
Officers attended and an extensive search was carried out, with assistance from the Bedfordshire, Cambridgeshire and Hertfordshire Dog Unit.
Three males were arrested a short time later.
A cannabis factory was subsequently discovered inside the property.
Detective Constable Neeluja Thisaveerasingam, from the Hertsmere Local Crime Unit, said: “Members of the public may have seen a high police presence in the area. I’d like to reassure them that no one was hurt and our enquiries into the matter are continuing at this time.
“If you have any information which may assist our ongoing investigation, please get in touch.”
Anyone with information is asked to please contact DC Thisaveerasingam via email.