BOSTON (AP) – The Boston Police Department has issued a safety alert to officers warning of a new gun found on city streets whose bullets can pierce some police vests.

The weapon, called a FN Five-Seven Handgun, fires bullets at such a high speed, they can punch through a bulletproof vest, according to the safety alert obtained by The Boston Globe.

The gun’s appearance on Boston streets was discovered last week, when two men were shot with it in separate incidents. It was unclear if the same gun was used in each episode.

“These aren’t recreational weapons,” Police Commissioner Kathleen M. O’Toole said. “This is an example of a gun designed to kill people.”

The weapon was first sold in the U.S. in early 2004. It began appearing in cities nationwide later that year, and the federal Department of Homeland Security sent out a warning about the gun and ammunition.

The gun is sold to the public, as well as military and law enforcement. The bullets sold to the public, however, do not have an armor-piercing tip and are designed to fragment upon impact, making them less powerful than those sold to the military and law enforcement. Those have a steel-hardened tip, making them able to penetrate thicker body armor.

Company officials defend the gun and say that when used with the ammunition that is sold to the public, it is similar to other handguns on the market.

Rick DeMilt, director of sales and marketing for FNH-USA, the U.S. subsidiary of FN Herstal, said the gun found by Boston police is sold for sporting purposes, such as hunting and competitive sports shooting.

It is unclear which kind of ammunition was found by Boston police.