Boston Mayor Marty Walsh on Monday signed an ordinance banning realistic-looking toy guys in public, saying that replica firearms were increasingly being used in real crimes and raised the risks of police officers firing on an unarmed person.

The measure comes in a year that Boston police have recovered more than 150 fake handguns used as threatening props in real crimes and follows multiple cases across the United States where police shot people after mistaking their fake guns for the real thing.

"Replica guns have become a big issue for us," said Boston Police Commissioner William Evans. "We all too often encounter young people who are carrying these fake guns and even though they are fake, the public and police don't know they are."

Under the terms of the new rule, police will confiscate realistic-looking firearms when they encounter them in public, whether in the hands of a child or adult. Owners 18 or older will be able to collect their replica weapons, which remain legal to possess and use on private property, at police stations.

The ban does not go as far one put in place in New York City, which requires that all toy guns sold in city limits to be brightly colored, while New York is one of seven U.S. states to limit sales of realistic looking toy guys, generally requiring they marks on the sides and tips of their barrels making clear that they are not real firearms.

Cleveland saw a wave of protests last year after a police officer fatally shot a 12-year-old boy who was carrying a toy gun, though an outside review last month found the shooting was a reasonable response to a perceived threat.