The difference between a toy gun and a real one is very blurry sometimes and that has led to unintended deaths.

New York State has witnessed four of those instances since 1997 and it's now trying to curb illegal toy gun sales at major retailers, such as Amazon (AMZN), Wal-Mart (WMT) and Sears (SHLD).

New York Attorney General Eric Schneiderman's office sent cease-and-desist letters Thursday to retailers telling them to stop selling illegal toy guns in stores and online in the state. Under state law, toy guns must have an orange stripe on the barrel of the gun. State law prohibits toy guns colored in black, silver or aluminum unless they have the stripe.

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"When toy guns are mistaken for real guns, there can be tragic consequences," said Schneiderman. "New York State law is clear: retailers cannot put children and law enforcement at risk by selling toy guns that are virtually indistinguishable from the real thing."

State investigators ordered illegal toy guns online and bought one at a K-Mart store near Rochester, N.Y. Some toy guns were even advertised as "realistic looking," according to the attorney general's office.

Wal-Mart and Sears said they are working to prevent illegal toy gun sales in New York online and in its stores.

"Once this matter was brought to our attention we placed a shipping block on our website to prevent the mentioned items from being sent to the state of New York," Wal-Mart said in a statement.

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Amazon and ToyArsenal.com did not return a request for comment.

Toy guns have come under heated, national scrutiny recently for the Nov. 22 death of 12-year-old Tamir Rice in Cleveland, Ohio. Rice was allegedly holding a toy gun when a police officer shot him.