Police in Montgomery County are warning residents about potential utility scams after incidents in Chevy Chase and Bethesda on Oct. 26.

In a press release, county police said a man wearing a hard hat knocked on an 87-year-old woman’s door at 11:35 a.m. and told her he worked for the Bethesda Water Co. He told her that there had been a main break and that he needed to check her water pressure.

When a neighbor arrived, police said, the man left without entering the house.

At 11:50 a.m., police said, a man in a hard hat knocked on an 86-year-old woman’s door and made a similar claim. When the woman accompanied the man to the basement, police said, she heard footsteps upstairs and later found jewelry missing from her bedroom.

Detectives ask anyone with information about these incidents to call them at 301-657-0112, and they caution residents to be wary because of increased utility work in the area in the aftermath of Sandy.