A cannabis farm with an estimated annual yield of more than £1.6m has been uncovered by police in St Helens.
Merseyside Police received a report at 1.15pm on Tuesday that a man had smashed a window at a property on Junction Lane.
Officers executed a Misuse Of Drugs Act warrant after discovering there was a cannabis farm inside.
The 411 plants were in five rooms across two floors in the house, along with growing equipment. The electricity had been abstracted.
Ch Insp Matt Drennan said: "Cannabis cultivation by criminal gangs can and does cause serious harm in our communities.
"Criminal groups involved in cultivating cannabis are usually involved in other serious organised crime and often use residential properties in the heart of our communities, such as this.
"Our communities can help us stop these groups, who are only interested in making money, from turning houses like this one into potential death traps. Nobody wants to live next door to these places and we would ask that if you believe someone is using a property for this purpose, please tell us so we can take positive action and find those responsible for setting them up.
"These farms will generally have a number of hot lamps hooked to overloaded electricity sockets as well as an extensive watering system. Electricity and water are never a good combination, and the fire service has attended fires that have resulted from fires caused by the crude systems put in place by the people who set up these farms."
Some of the signs that cannabis is being grown are:
• Strange smells and sounds
• Frequent and varied visitors to a property, often at unusual times
• Gardening equipment being taken into a property, such as plant pots, fertiliser, fans and industrial lighting
• Windows are sealed and covered or the curtains are permanently closed
• Heat from an adjoining property
• Birds gathering on a roof in cold weather
Anyone with any information is asked to call police on 101, or Crimestoppers, anonymously, on 0800 555 111.