Police have warned residents to be on their guard following reports of 'bogus callers' offering to do roof and guttering work.
The majority of the reports have been from the Cleveleys area and are targeting the elderly.
A Lancashire Police spokesman said: " The only information police have at the moment is that they are driving a newish white transit van and there are up to four males.
"They are targeting vulnerable elderly residents.
"Please can you call 101 if you see anything suspicious in your area and if possible get a registration number for any vehicles you have concerns about."