Portland police on Sunday confirmed they are investigating a string of vandalism and potential burglaries affecting businesses in downtown Portland as well as the Old Port district.

At least two businesses located on Wharf Street were vandalized with investigators treating the incidents as potential burglaries, police department spokesman David Singer said in an email.

Portland Flea For All, a flea market on Congress Street, on Sunday posted multiple images of vandalism to its building on Instagram.

“Not one, not two, but three smashed windows,” Portland Flea For All owners wrote on their Instagram page. “If you see a guy with a bat on a bike, gird your windows. We’re theoretically the fourth target this week.”

News Center Maine reported that windows were recently shattered at Reny’s department store on Congress Street and at Jefe Juans, a restaurant and bar on Wharf Street.

On Sept. 19, Portland police arrested 39-year-old Jimmy Burnett after he allegedly broke into several businesses on Monument Square in Portland. Burnett broke windows and other items to get into David’s Restaurant and The Lady in the Moon, a boutique store, according to Portland police. Officers responded to reports of vandalism and found that several business had damaged storefronts, including broken windows. The Lady in the Moon had a large hole smashed in a window, and other businesses had overturned and damaged exterior tables and chairs.