Police have named three men who died separately in just over an hour in Lancashire in what officers believe are heroin-related incidents.
Detectives said that a strong batch of the drug being sold on the streets of north-east Lancashire may have caused the deaths on Friday and Saturday.
Robin Ferguson, 53, Emlyn Hodgkinson, 36, and Zaheer Chaudrey, 32, were found at separate addresses after 2315 GMT.
Post-mortem examinations have not yet been carried out on the men.
Mr Ferguson was found at a house in Tennis Street, Burnley, at 2315 and 20 minutes later the body of Mr Hodgkinson was discovered by officers at Oak Street, Colne.
At about 0020 GMT on Saturday, the body of Mr Chaudrey was discovered at a house in Eagle Street, Nelson.
Det Ch Insp Stuart Dixon, of Lancashire Police, said: "From our inquiries today we believe that there may be a strong batch of heroin in the area and I would urge anyone who uses this drug to contact their local drug support agency.
"There could be an increased risk in taking stronger heroin and users should seek help and advice if concerned.
"At this current stage we are treating the deaths of these men as unexplained.
"Drugs could possibly have been a factor and once the post-mortem examinations take place and we know the outcomes then we will be in a position to understand exactly how these men have died.