The Garage mall in Harvard Square has seen three thefts since mid-March, two of purses and another of a wallet from a purse — part of an increase in such crimes throughout the area. (Photo: Ian Lamont)

Watch your stuff.

There has been a rash of wallet, purse and cell phone thefts — about 25 since mid-March — mainly in Central and Harvard squares. (Police are putting emphasis on Harvard Square, which they identify as the site of 13 of the incidents.) Almost all of the crimes have been the taking of items from purses hanging on the back of chairs or put under chairs, or theft of the purses themselves.

Coffee shops are particularly targeted: four thefts reported from Crema at 27 Brattle St.; three from the Clear Conscious Café at 581 Massachusetts Ave.; two from the 1369 Coffee House at 1369 Cambridge St.; and one each from the Dunkin’ Donuts at 616 Massachusetts Ave., Sofra Bakery at 1 Belmont St. and Starbucks at 36 John F. Kennedy St. That Starbucks is in The Garage mall in Harvard Square, which has also seen thefts from its Flat Patties and Felipe’s Taqueria eateries.

Other places in Harvard Square that seem to be part of the trend: Charlie’s Kitchen, the Border Café and an unidentified “Arrow Street workplace.” In Central Square, the McDonald’s, Middle East, library and Rangzen Tibet restaurant have seen a theft, and the Goodwill has seen two. There was also a theft at the Marriott at 2 Cambridge Center in Kendall Square.

Any of these may have been independent crimes of opportunity, and police are not ready to say there is one or more people on a spree, Cambridge Police Department spokeswoman Emily Wright said Monday, “just that there is an increase.”

In the first half of the month, there were 10 or fewer crimes fitting this pattern, adding to the mix Toscanini’s in Central Square, the Cambridge Cafe in Kendall Square and Peet’s Coffee & Tea in Harvard Square. McDonald’s and the Clear Conscience Café saw one more larceny each.

“There isn’t as much of a pattern as you would suspect,” Wright said. “We are trying to get more description.”

Descriptions offered by victims have been too vague to determine whether it’s the same person or people committing the crimes, she said — even from the woman who was alert enough at 2:41 p.m. March 13 to stop the theft of her wallet from her purse.