A highly dangerous method of producing super-strength cannabis is emerging in the UK, police and firefighters say.
Butane hash oil is made using large amounts of the flammable gas, which can explode with devastating consequences.
A BBC investigation has learned of two deaths and 27 people being injured across the UK since 2014, as a result of making the drug.
The warning comes on the same day a Glasgow man was jailed for more than six years after his drug lab exploded.
Butane hash oil (BHO), which is illegal in the UK, is also known as honey oil, dabs or shatter.
Pure and strong
It is pure and strong and made by using solvents to strip out of cannabis plants one of the active ingredients of the drug - THC.
Producers often use butane gas, which can ignite and cause a fireball.
It has become popular in the US, especially in states where cannabis has been partly decriminalised.
In Colorado there were more than 30 explosions linked to BHO in 2014 alone.
Now there is evidence that it is coming to the UK.
"They're using the butane as a solvent to extract the products they require," explains John Galvin from Fire Investigations UK.
He demonstrates how the production process works. The gas is heavier than air, sticks to clothes and pools on the floor.
Mr Galvin also explains that it takes very little to ignite it.
"Flicking a light switch, or it could be a fridge switching on and off," he adds.
Court told of drug lab blast
Several people were badly injured and a dog and cat were killed when a home-made drug lab exploded, causing damage estimated at £1m to a Glasgow tenement, a court has heard.
Scott Peden, 30, was bidding to make a super-strength form of cannabis at the flat in Tollcross when the equipment caught fire and blew up on 21 March. He has been jailed for six years and four months.
The High Court in Glasgow was told gas released during the drug-making process ignited and caused an explosion, possibly due to a light being turned on.
Windows and the front door of the flat were instantly blown off in the blast.
Passing sentence, judge Lord Armstrong told Peden that he had shown "gross irresponsibility" and that his actions had had "traumatic and devastating consequences".
There were just four injuries from production of the drug in the UK between 2010 and 2014.
Alex Fraser, who has been campaigning for medicinal use of cannabis to be legalised, says BHO is becoming increasingly popular.
"It's huge - comparative to last year, it's 10 times bigger and I expect it will be 10 times bigger next year."
But he fears more people may try to make it themselves and get injured.
An explosion at house in Birmingham in November 2014 left one man dead.
The house was destroyed and hundreds of butane canisters were found in the property.
West Midlands Fire Service investigator James McDonald calls the people who make BHO "YouTube chemists".
There have been six explosions in his area since 2014 - two in the last month alone.
His message is simple: "Do not try this... the devastation... the effects on people's lives is incredible."
During Scott Peden's case, the court heard fire crews found "absolute carnage" when they attended the aftermath of the blast.
Eight people were injured and 50 firefighters tackled the blaze that followed.
Detective Inspector David Stewart, of Shettleston CID, said: "I cannot emphasise enough the stupidity of his selfish actions."
Also on Friday, two men from Dudley, in the West Midlands, were each jailed for three years after blowing up a house in October last year when producing cannabis in the same way.
The National Police Chief's Council for England and Wales says officers will "target anyone producing and selling cannabis in whatever form".