Ottawa police say organized criminals seeking cash and jewelry have been bypassing ground-level cameras on people’s homes by using ladders to gain entry through upstairs windows and doors.

In a news release issued Friday, Ottawa police said criminal gangs are believed to be behind a recent rise in residential break-ins using this method. Police denied a request for an interview about the trend, which they say is happening across the city.

According to the news release, suspects dressed in dark clothes and carrying backpacks park up to a kilometre from their targets and walk the rest of the way. They often use stolen or rented vehicles, and strike both during the day and at night.

Police say the thieves typically target homes that back onto greenspaces such as golf courses. They either bring their own collapsible ladders or use the homeowner’s ladder or patio furniture to reach the second floor, police said.

The thieves sometimes toss pebbles at windows to see if anyone’s home, police said. Investigators believe they’ve adopted these methods to avoid doorbell and perimeter cameras now common on many homes.

Police recommend adding second-floor cameras or repositioning existing ones to increase coverage. Homeowners should also store valuables in safes or safety deposit boxes that can’t be removed, and be sure to keep all windows and doors locked, police said.

Anyone witnessing a crime in progress should call 911, police advise.