The advent of 3D-printed guns has stirred much debate and concern among the federal government and gun legislation activists. Now, Philadelphia has passed a city measure that bans those without a firearms manufacturing license to make 3D guns.

The measure unanimously passed the Philadelphia City Council which makes Philadelphia the first city to pass a law of its kind. Just in a few short weeks, a federal ban on guns undetectable by metal detectors will expire. Despite enacting a measure seemingly written with incredible foresight, Philadelphia director of legislation didn’t offer much insight on the reasoning behind the bill.

“It’s all preemptive,” said director of legislation Steve Cobb. “It’s just based upon internet stuff out there.” However, bill author and city councilman Kenyatta Johnson was able to be more clear about the bill and why he wrote it.

“As technology progresses, three-dimensional printers will become more advanced, less expensive, and more commonplace,” said Johnson. “As instructions for the manufacture of guns via 3D printing technology are already available on the Internet, we could be looking for a recipe for disaster.”

ThinkProgress has reported that other states, like New York, California, and Washington D.C., and municipalities are pursuing the enactment of similar laws. The Bureau of Alcohol, Tobacco, Firearms, and Explosives tested the 3D gun model model, the Liberator. The ATF found the weapon powerful enough to damage vital organs if shot at a person.

When the schematics became open sourced in May, they were downloaded over 100,000 times, according to the ATF.

During the ATF’s test firing, not only did the bureau find the weapon dangerous to someone on the receiving end of a round, but the shooter is also in danger. If the the manufacturing material isn’t strong enough, the gun would explode right in the shooter’s hands.

3D printed guns are a safety concern, not only for the chance of gun violence, but also because of the dangers imposed on the operator.

“Manufacturers have research and development, and they make sure products they put out have been vetted and tested,” said ATF spokesman Tim Graden. “These, not so much.”

Josh is a writer and researcher with Ring of Fire. Follow him on Twitter @dnJdeli.