Police in Portland are warning about a string of commercial burglaries this month.

The department says five burglaries were reported between Jan. 9 and Jan. 17. They occurred on Forest Avenue, Hanover Street, Union Street, Warren Avenue and Washington Avenue.

Some of those incidents involved burglars entering through windows where a fan or air conditioner had been installed. Cash and copper have been stolen.

Local businessowners are being reminded to secure or lock their windows.

Police said that in some case the wires to burglar alarms had been cut. They’re urging businesses to check any security alarms that occur, and that if they don’t have a security system installed, to consider doing so.