DULUTH, MN (KDAL) - The Duluth Police Department is advising the public to be aware of a crime pattern that has developed over the last several weeks. Construction sites have seen break-ins to trailers and vehicles used to store tools and building materials. Structures that are under construction have also been broken into and with tools and other materials taken. Contractors and homeowners are being reminded to take extra efforts to secure tools and other valuable materials that are left unattended at construction sites. Marking items and recording serial numbers would help law enforcement in recovering and returning items if you are victim of these crimes. The public is being urged to report any suspicious activity at construction sites by calling 911.