Since November, at least four school shootings had an alarming connection to law enforcement and activists alike; the suspected shooters used a "ghost gun." A "ghost gun" is a firearm that comes packaged in parts, can be bought online and assembled without much of a trace, which experts warn are becoming increasingly dangerous.

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There are two types of weapons that fall under the ghost gun moniker, according to McCourt. The first is a plastic gun that can be made with a 3D printer and usually fires one bullet. The second version, which he said has been increasingly found at crime scenes, is do-it-yourself gun assembly kits that include all the parts of a gun, but without serial numbers or specific components. McCourt said these homemade guns bypass federal laws requiring registration and tracing.

Due to loopholes in federal gun laws, the kits are not considered firearms because they are missing specific completed components. In addition, under current laws, users aren't allowed to register their constructed weapons with the federal government.

https://www.msn.com/en-us/news/crime/ghost-guns-showing-up-in-school-shootings-experts-fear-trend-will-get-worse/ar-AAVb63l?li=BBnb7Kz