By Dan Koob

PHILADELPHIA (CBS) — Several men are under arrest, accused of fueling Philadelphia’s gun violence. Prosecutors say they’re doing this with weapons built from scratch and difficult to trace.

Authorities say 10 ghost guns were seized in two separate operations, putting four people behind bars. Police say there are more of these untraceable firearms showing up on our streets.

READ MORE: Teenager Killed In Trenton Shooting Identified As Shemiah Davis, Mercer County Prosecutor's Office Says

“The ghost guns we seized this week all started out as an 80% receiver, looking just like this,” Pennsylvania Attorney General Josh Shapiro said.

(Credit: CBS3)

Shapiro says 19-year-old Najaye Davis and a coconspirator purchased multiple 80% receivers and gun kits with cash at a Morgantown gun show last month without a background check and brought them back to Philadelphia. The investigation also found more than 1,000 rounds of ammunition.

According to the attorney general, Davis sold Ghost guns at $500 profit per sale and described these untraceable guns as the preferred weapons of criminals.

Najaye Davis

“In all of 2019, together with our law enforcement partners, we recovered 99 of these ghost guns,” Shapiro said. “In just the first two months of this year, we have recovered over 80 of them.”

READ MORE: Apartment Fire In Norwood Leaves Several People Injured

A second investigation yielded similar results.

The Attorney General’s Office says Malachi Matthews and Kenneth Manni were found to have purchased four gun kits at the same show. Also found were two unserialized ghost guns and fentanyl in their possession.

Malachi Matthews and Kenneth Manni

City and federal laws don’t consider an 80% receiver a fully formed gun, thereby allowing a buyer to forego a background check. Both cases will be prosecuted by the District Attorney’s Office.

“There’s no good use for a plastic gun no a serial number,” Philadelphia District Attorney Larry Krasner said. “It’s for terrorists and it’s for crime.”

MORE NEWS: South Jersey Family Helping Those Affected By Ida In Louisiana

“It is clearly not enough to take illegal firearms off the street,” Philadelphia Police Commissioner Danielle Outlaw said. “We also need to stop the individuals who are supplying them in the first place.”