Thrill-seeking teenagers have been warned they are putting their lives at risk by running and jumping across roofs.
Incidents of the precarious craze have been on the increase in Chorley town
In addition to annoying residents and traders, the youths are causing damage and are in danger of seriously injuring themselves.
Police say they are prepared to prosecute anyone they catch.
PCSO Fern Jones, of the Chorley town centre neighbourhood policing team, said: “We’ve had numerous incidents. A lot haven’t been rung through – we’ve come across people on roofs. It’s about ten incidents in the last six or eight months.
“It’s been happening along the Chapel Street, St George’s Street shops. The main area is over Quality Save. They’ve moved. They were on the Argos area on Market street.”
She added: “We’ve also had quite a bit of damage up there as well. There have been a lot of roof tiles broken.
“One firm, McVerry’s printers, have had cameras put up. The free runners have been up and decided to smash all the cameras which is £500-plus damage. We are still investigating. We are prepared to prosecute.
“In the last couple of weeks, we’ve taken about ten youths back to their parents and explained what has gone on and if the pictures come back it’s their kids, they are going to be dealt with.
“It’s extremely dangerous. It’s very high up there. The roofs aren’t a secure place to walk, run or jump on.
Sgt Kevin Mountain, of the Chorley neighbourhood policing team, said: “There have been a number of incidents recently.
“This is extremely dangerous and it’s a waste of our time. Parents should know where their children are and what they are up to.”
Malcolm Allen, who runs Malcolm’s Musicland, Chapel Street, and is chairman of the Chorley Traders’ Alliance, said: “It’s a constant problem within the town centre.
“If they are into that, should we be channelling it into some other activities for them?”
Coun Peter Wilson, deputy Leader of Chorley Council, said: “We know young people feel there is a shortage of things to do in the town centre and that’s why we are under way with creating a youth zone.
“It would provide a wide variety of activities for young people in a safe place and would hopefully prevent them from resorting to things like roof running.”