The teen was arrested Friday on charges of harassment and bias intimidation. Authorities said he was released to the custody of his parents; they did not know whether he had a lawyer.
"This was an extremely disturbing event on many levels," Gloucester County Prosecutor Sean Dalton said at a news conference. "Any statements like these that can cause harm or grave concern must be addressed as quickly we possibly can."
Authorities would not say whether the announcement was planned or made impulsively. Police said they were also investigating a teenage boy who accompanied the suspect to the store, but had not charged the other boy.
Although a manager quickly went on the intercom system and apologized for the remark, many customers expressed their anger to store management.
Officials for Bentonville, Ark.-based Wal-Mart Stores Inc., said the announcement was "unacceptable." Spokesman David Tovar said the company planned to release a statement later Saturday, after the news conference.
The company said it has already updated the store's intercom system to prevent a similar incident from happening again.
It was the latest in a series of problems the retailer has had in its dealings with minorities and women.
There have been several past instances of black customers claiming they were treated unfairly at Walmart stores, and the company faced lawsuits alleging that women were passed over in favor of men for pay raises and promotions.
In February 2009, the retailer paid $17.5 million to settle a class action lawsuit alleging racial discrimination in its hiring of truck drivers.
And the U.S. Equal Employment Opportunity Commission sued the company in May 2009, claiming some Hispanic employees at a Sam's Club subsidiary in California were subjected to a hostile work environment. That suit alleges managers failed to stop repeated verbal harassment, including the use of derogatory words, against employees of Mexican descent.
However, the National Association for the Advancement of Colored People has said the company has worked hard in recent years to show it cares about diversity.