A shoplifting ring at the Walmart Superstore in Clarence was apparently broken up Monday, when state police charged four employees with stealing thousands of dollars by not ringing up merchandise or scamming customers who had gift cards.

State police said Tuesday that troopers arrested two people on grand larceny charges and two more on petit larceny charges, after a monthlong investigation by officials at the Walmart on Transit Road.

Walmart contacted state police Monday with evidence that several of their employees had been “underscanning” or “underringing” merchandise.

The four are accused of allowing accomplices to go through their checkout lines and leave the store without paying for numerous items worth an estimated $7,000 or more that were not scanned or rung up, police said.

On other occasions, the cashier would activate a gift card for a customer, keep it and then swap it with another card, leaving the unsuspecting customer to walk out of the store with a card that could not be used, police added.

The investigation is continuing, and more arrests are pending.

The four arrested:

• Evelyn C. Smith, 26, of Buffalo, who was charged with fourth-degree grand larceny. Smith is accused of underscanning at least seven times for a total of $2,600 worth of merchandise, police said.

Smith also is accused of going through the checkout line as a customer and leaving the store with roughly $1,600 worth of unpaid goods.

• Tacara Lawrence, 21, of Buffalo, also was charged with fourth-degree grand larceny for underscanning on at least four occasions and allowing accomplices to get away with roughly $2,500 in merchandise.

• Dewayne Harrell, 22, of Buffalo, who was charged with petit larceny. He’s accused of stealing two gift cards totaling $95, when he activated the gift cards for two customers and then switched them with cards that had not been activated. Harrell kept the activated gift cards for himself, police said.

• Latasha M. Morrow, 19, of Buffalo, who was also charged with petit larceny.

Morrow is accused of leaving Walmart with about $280 worth of merchandise, which initially had been scanned then voided by one of the cashiers involved in the ring.