Thieves may again be watching as women leave purses behind when they briefly step out of their cars in Howard County, police said. And when a woman leaves the purse, the thieves swoop in, smash the window and take the item, police said.

They said four purses taken Wednesday appear to be part of a trend observed up and down the East Coast.

In a rash of similar incidents in Howard County early this year, police said, the thieves got enough personal data to drain bank accounts.

On Wednesday, they said, purses were taken from the cars of three women who dashed into day-care centers to pick up children. The fourth theft occurred outside a gym.

Police have urged women to never leave their purses behind, even if they step out of their cars for only a minute. Significantly, police said hiding the item wouldn’t work. Thieves who watch women walk away from their cars without purses, police said, know that the item has probably been left behind.