PLAINVILLE (CBS) – Police say they’re dealing with a rash of thefts that’s costing local charities thousands of dollars.

“We have had an epidemic problem,” says Plainville Police Sgt. Corrina Carter. She says police have caught thieves stealing from bins of donated clothes and household items 17 times since the beginning of the year, and more than 300 times in 3 years.

The biggest target is the Society of St. Vincent De Paul Thrift Store. Sunday night, officers arrested a mother from Brockton, her 18-year-old son, and two younger teenagers. One of them was inside the bin, throwing bags out to someone else who loaded them into a truck.

Police say the thefts are part of an organized ring. “The better labels on the clothing are being sold at swap meets, at flea markets, and on the Internet. The lesser-known labels are being sent out of the country, so that their families in other countries can sell them,” says Carter.

The Society of St. Vincent De Paul charity sells used items for low prices, and uses the money earned to help families in need.

“Ultimately, they’re hurting those less fortunate,” says Carter.