(KRON) — Four suspects have been arrested in connection to a series of armed robberies in East Oakland that targeted victims for construction tools, according to the Oakland Police Department. The four armed individuals, described as two adults and two juveniles, are linked to at least nine armed robberies in the last three months, OPD said.

Officers recovered four firearms, a replica firearm and evidence related to the robberies when serving search warrants at the homes of the four suspects. Two of the recovered firearms were equipped with devices that transformed them from semi-automatic to full automatic with the single pull of a trigger, police said.

The arrests were a collaborative effort between OPD officers with the Violent Crime Operations Center, Ceasefire Division, Criminal Investigation Division, Intelligence Unit, Community Resource Officers, Air Support Unit, Tactical Team and non-affiliated agencies including the US Marshal Service, ATF and CHP.