Huntington Park police arrested a man this week who they say was posing as a federal immigration agent.

At a Friday news conference, the Huntington Park police chief and mayor discussed the arrest of 24-year-old Fernando Diaz, who they say was impersonating a federal agent, using it as an example of what they say is a broader issue.

However, a spokesperson from the Los Angeles County District Attorney's Office said there was insufficient evidence to file impersonation charges. Prosecutors charged Diaz with weapons violations, and he was placed in a diversion program. 

Diaz was arrested on June 24 after officers spotted a gray Dodge Durango parked in a handicap spot with no visible handicap placard and without a front license plate. 

Police Chief Cosme Lozano said officers thought the truck might be an unmarked law enforcement vehicle after spotting several police-like radios and a firearm magazine inside the SUV.

Vehicle registration information showed that it was registered to a person in Los Angeles, not law enforcement.

"The officers then initiated procedures to impound the vehicle for violations of the California vehicle code, and as they were doing so, a male individual approached, claiming to be the owner of the vehicle," Lozano said.

Diaz claimed the items in the truck belonged to a friend, investigators said. Diaz also told officers that he works as a security guard and stated that he had previously worked for Customs and Border Protection; however, police say he was unable to produce any valid credentials to substantiate this claim.

A further search of the vehicle revealed a loaded 9mm semi-automatic firearm, two holsters, additional ammunition for the gun, three cell phones, a sheet containing U.S. Customs and Border Protection radio codes, multiple copies of passports, red and blue lights hidden under the vehicles visors … "and other miscellaneous items indicative of possible criminal activity," Lozano said.

Huntington Park Mayor Arturo Flores said residents across the region are reporting encounters with individuals claiming to be federal agents.

"One recent incident prompted a resident to ask, 'Who are these people?' And frankly, the vests that they were wearing look a lot like they were ordered on Amazon, " Flores said. "Are they bounty hunters? Are they vigilantes? These questions reflect a larger breakdown of trust and accountability." 

During the news conference, Flores added that the Huntington Park City Council passed a resolution this week directing its police department to verify the identity of anyone claiming to be a federal immigration agent in the city.  

CBS News Los Angeles has reached out to the Department of Homeland Security and are waiting for a response.