POLICE ducked for cover as a metal shotgun ammunition box containing 126 bags of cannabis was hurled from a first-floor window.
Officers were trying to force entry through the front door of the semi-detached house in Tintern Road, Carshalton, when the heavy metal object smashed into a patio paving slab as it crashed to the ground.
The ammunition box was taken to Sutton Police Station, where it was opened and found to contain 120 "snap" bags and six larger bags of suspected cannabis.
While searching the property, the officers also found around 15 snap bags of white powder – believed to be a Class A drug.
Two women aged 42 and 28 were arrested following last Friday's raid.
In a separate drugs bust on Tuesday, a 28-year-old man was arrested after police found a cannabis factory at a house in Church Hill Road, Sutton.
Officers found 60 cannabis plants in an outbuilding in the back garden, while a search of the address also uncovered a quantity of CS and pepper spray. Chief Inspector Nick Collins said this week's arrests were a signal that the police were getting tough on drugs in Sutton.
He said: "Residents are rightly concerned when they believe that drugs are being bought, sold and grown in their neighbourhoods. We have been actively encouraging residents to pass on any information they have about suspicious individuals and addresses.
"This information is developed by local police teams and, combined with information from our own intelligence unit, results in the drugs raids and operations that we carry out on a regular basis around the borough.
"Residents should not have to put up with drugs-related activities on their doorstep. Drugs are a blight on local communities and only tend to encourage more crime.
"We want to continue to encourage residents to help us and we will continue to be robust and relentless in the pursuit of anyone involved in drugs-related crime."
Officers are contacting property management companies, letting agents and landlords to advise them to check their properties regularly to ensure they are not being used for the cultivation of drugs.