Police are investigating the deaths of three men who died separately in heroin-related incidents in just over an hour.
The bodies of Robin Ferguson, 53, Emlyn Hodgkinson, 36, and Zaheer Chaudrey, 32, were all discovered late on Friday night.
Detectives fear that a strong batch of heroin could be in the supply chain on the streets of north-east Lancashire where the deaths happened.
Mr Ferguson was found at a house in Tennis Street, Burnley, at 11.15pm on Friday. Nearly 20 minutes later, police were called to Oak Street, Colne, where they discovered Mr Hodgkinson.
Then, at about 12.20am, the body of Mr Chaudrey was discovered at a house in Eagle Street, Nelson.
Post-mortem examinations have yet to take place on all three bodies, however it is thought that drugs may have been a factor in their deaths.
Det Ch Insp Stuart Dixon said: "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.
"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.
"Anyone who has any information around the supply of drugs should come forward and contact police or people can call Crimestoppers anonymously with information."
Anyone with information should contact Burnley police on 01282 425001 or call Crimestoppers anonymously on 0800 555 111.