Massachusetts has banned the purchase of military-style assault weapons and high-capacity magazines within the state since 2004, but after firearms made in the Bay State have been used in multiple mass shootings elsewhere, a group of lawmakers now wants to prevent them from being built here as well.

Several Democrats in the Legislature filed a bill Tuesday (HD 4192) that would prohibit Massachusetts companies such as Smith & Wesson, headquartered in Springfield, from manufacturing weapons and devices covered under the existing ban, exempting those that would be sold to law enforcement, the military or foreign governments.

"If we no longer produce and manufacture military-style assault weapons here in Massachusetts and we impact the ability for private citizens to access these weapons, we know there will be fewer mass shootings," said Rep. Marjorie Decker, a Cambridge Democrat and one of the bill's authors. "We know less people will die."

Supporters, including the Stop Handgun Violence organization, say three other states — California, New York and New Jersey — have a ban on the manufacturing of assault weapons. The legislation would not affect handguns, which are used in a significant majority of gun violence incidents, or any other weapons that are permitted for purchase in Massachusetts.

Several lawmakers pushing for the bill describe the fact that companies can manufacture assault weapons in Massachusetts and sell them in other states as a "loophole" in the existing ban. They unveiled their proposal at a virtual press conference alongside parents whose children were killed in mass shootings using weapons built in Massachusetts.

"These weapons are made in your state, but they cannot be sold in your state, so in effect, Massachusetts is exporting bloodshed to the rest of your country," said Sandy Phillips, whose daughter was killed in a 2012 mass shooting in Aurora, Colorado.