On the outside, it looked like a normal storefront on Metropolitan Parkway in southwest Atlanta.

But the customers were mostly felons who came to the store to sell guns and drugs, and the "employees" were actually undercover agents, U.S. Attorney Sally Qullian Yates said Wednesday.

"They put the word on the street that they were interested in buying guns and drugs, and the criminals came knocking," Yates said.

When all of the arrests are made, 60 suspects will be off the streets, along with 270 illegal firearms and thousands of dollars worth of drugs. Some 33 rifles, 25 shotguns, seven sawed-off shotguns and three smoke grenades were taken straight from the hands of would-be criminals, many of them already convicted felons, Yates said. Forty suspects are expected to face federal firearms and drug trafficking charges, she said.

"Operation Trapdoor" involved federal, state and local law enforcement, including Atlanta police, ATF and federal marshals, and cost about $150,000 to pull off, Scott Sweetow, special agent in charge with the ATF said.

"We consider it a very good return on our investment," Sweetow said of the 14-month operation.

The arrests started early Wednesday, Sweetow said, and the majority of the suspects were in custody by late afternoon. Investigators expect to have the remaining suspects in custody soon.

In addition to getting the weapons and drugs off the street, the would-be suspects also offered tips to undercover agents about other crimes at the fake store, called Metro Mobile Safes, Sweetow said. One of the guns confiscated in the operation had been used in an Alabama homicide, he said.

"These are not nice folks," Sweetow said. "They did not come to our storefront to sell us Bibles and Blue Bell ice cream."

Among those arrested Wednesday in the operation are two 20-year-olds from Atlanta, seven from Clayton County, and four Cobb County residents. Several others arrested are also from Atlanta.

The most recent "storefront" sting is the second in a year in Atlanta. Last June, "Operation ATL Blaze" led to the arrest of 49 suspects, including 35 charged federally.