LYNN, Mass. (WPRI) — Three Massachusetts residents were arrested Wednesday following a months-long drug trafficking investigation.

The investigation was conducted at the direction of Attorney General Maura Healey, according to Massachusetts State Police, and included “several controlled purchases of fentanyl and methamphetamine pills from three targets by an undercover trooper.”

Investigators executed two search warrants at apartments in Lynn and Salem Wednesday morning, during which they found hundreds of pressed fentanyl and methamphetamine pills, several pounds of marijuana and two loaded semi-automatic pistols, according to police.

Police said approximately 250 of those pills were found hidden in a dog crate under a pit bull named “Kilo.” The pills, according to police, were secreted underneath Kilo’s bedding in the Lynn apartment.

Kilo, who police said was “very friendly,” was removed from the crate and transported to the North Shore Animal Hospital.

The dog’s owners, Lynn residents Andre Wesley, 34, and Giselle Gonzalez, 28, were taken into custody.

Police said the marijuana and an additional 160 pills were found inside the Salem apartment, as well as the loaded pistols and several rounds of ammunition. The resident of that apartment, Joell Sosa, 24, was also arrested.

Healey’s office is prosecuting all three suspects, though police didn’t specify the charges they’re facing.