In January, federal agents tracing the origins of components that turn handguns into automatic weapons were led to a modest home in Roxbury. There, in a back bedroom of his mother’s apartment, federal agents allege 23-year-old Michael Wilkerson and a friend used a 3-D printer to churn out small plastic devices that can quickly convert pistols to machine guns.

A cooperating witness had purchased a dozen of the devices for $1,700, leading to the arrest in February of Wilkerson and Elijah Navarro, 24, on federal gun manufacturing charges, according to filings in US District Court in Boston. Agents said they seized two 3-D printers, printing materials, and eight of the devices from Wilkerson’s bedroom during a search of the Homestead Street apartment.

Wilkerson and Navarro have pleaded not guilty in US District Court in Boston and are awaiting trial.

The case has cast a spotlight on an emerging problem in Massachusetts: The number of automatic guns used in street crimes is spiking, largely fueled by technology that can be used by anyone with knowledge of 3-D printing. They are commonly referred to as Glock switches, converters, or chips and have been linked to a wave of violent incidents: In Boston, for example, a 15-year-old girl was one of five people wounded by a gun using the device; in Springfield, police said the widening violence is reflected by a 75 percent increase in the number of shell casings recovered at shooting scenes this year.

Lawmakers and community activists are pushing for tougher state gun laws to crack down on the devices. Under federal law, possession of a switch is treated the same as having a machine gun, which is illegal unless permitted and registered. But under Massachusetts law, it’s only illegal if the device is attached to a gun; mere possession of the switch is not a crime.

For example, in Suffolk County this year, prosecutors have filed 13 charges involving Glock switches, up from four last year, data show. But prosecutors were unable to pursue charges related to the recovery of dozens of machine gun conversion devices in recent years because they were not attached to a gun, according to the Suffolk district attorney’s crime strategies bureau.

“There’s no reason for anyone to have these dangerous devices and we need to make them legally actionable at all stages, not just when they’re affixed to a weapon,’’ Suffolk DA Kevin Hayden said in a statement.

The devices may be easily created with a $200 printer and downloadable instructions readily available over the Internet, said James Ferguson, the special agent in charge of the Boston office of the Bureau of Alcohol, Tobacco, Firearms, and Explosives. The conversion devices are also sold on e-commerce websites and shipped from China, frequently advertised as keychains or wall hooks to avoid detection, he said.

Once the hooks of hardened plastic or metal are attached to a handgun, the weapon can fire up to 1,200 rounds a minute, according to Ferguson. They generally work on handguns manufactured by Glock or “ghost guns,’’ assembled from kits purchased online or using 3-D-printed components, and have Glock bases.

Ferguson said the proliferation of the devices makes him worry about a return to the old gangster era of the 1920s and 1930s, which were “a very violent time for our country’’ and led Congress to pass the National Firearms Act in 1934.

“We’re now seeing that pendulum coming back to where this technology is providing this availability of automatic fire to the everyday criminal,’’ Ferguson said during an interview.

Ferguson said the switches have plagued other cities, particularly in the South, for a number of years. Now, he said, they’re showing up in increasing numbers in Boston, Springfield, and other urban areas across the state.

In September, two men were charged with assault with intent to murder and possession of a machine gun in a shooting that wounded five people at the Franklin Field public housing complex in Dorchester. Prosecutors allege that the men used a machine gun conversion device. And in August, six men and two women were shot during the J’ouvert celebration in Dorchester. Police arrested a 30-year-old man on charges of attempted murder and possession of a machine gun, which had been converted to an automatic with one of the devices.

“If you’ve got guys that have the equivalent of a mini machine gun in their hand, we’re going to see violence at the levels we had 30 years ago if we’re not careful,’’ the Rev. Jeffrey Brown, a pastor at the 12th Baptist Church in Roxbury, said, referring to a time in Boston when homicides and street violence were at much higher levels before dropping in the 1990s.

In October, the Massachusetts House of Representatives passed an omnibus gun bill that includes an amendment banning the possession of unaffixed Glock switches and other parts that can make a gun automatic. The Senate is working on its own version of a gun bill.

“They just spray bullets through the whole community,’’ said Representative Russell Holmes, a Mattapan Democrat who introduced the Glock switch amendment. “The thought that someone could pull a trigger once and empty a clip is unacceptable.’’

State Senator John Velis, a Westfield Democrat, called the devices “a purveyor of death’’ and said, “There is absolutely zero reason to have a Glock switch except for causing maximum damage.’’

Gun Owners Action League executive director Jim Wallace acknowledged that Glock switches are dangerous, but said they’re already “super illegal’’ and authorities should focus on enforcing existing gun laws before they “rush to pass anything.’’

The maximum penalty for illegal possession of a machine gun is 10 years in prison under state law; and 15 years in prison under federal law.

Massachusetts court data show 75 charges were filed in the fiscal year that ended in June for possession of machine guns, up from 47 the previous year. The US attorney’s office in Massachusetts has charged 11 people with possession of a machine gun this year, and each case involved a switch. Over the previous four years, that office charged a total of four people with possessing a machine gun, of which two involved switches.

Two of those charged this year are Navarro and Wilkerson, who were indicted in March on charges of possession of a machine gun and unregistered firearms dealing. Navarro’s lawyer declined to comment, and a lawyer for Wilkerson did not respond to a request for comment.

According to an ATF affidavit filed in the case, Navarro agreed to sell a dozen conversion devices to the cooperating witness for $1,700, but initially only provided two, promising the rest would be ready soon. “I’m going to print everything,’’ the affidavit quotes Navarro telling the witness. Weeks later, he allegedly provided the rest.

The switches cause a recoil when a gun is fired that makes it difficult to aim, causing it to spray bullets in unpredictable directions, according to Springfield Police Captain Brian Keenan.

“People are getting hit, houses are getting hit,’’ he said. “Imagine that in your neighborhood, in front of your house, with children.’’

Sean Cotter can be reached at sean.cotter@globe.com. Follow him @cotterreporter.