PERRIS (CBSLA) — The deaths of three men found on top of a gravesite in a Perris cemetery Monday might be drug cartel related, Riverside County Sheriff Chad Bianco said Tuesday.

Bianco made the announcement in a morning conference to let residents know that there was no reason for them to be concerned about their own safety, and to say that these killings did not appear to be related to other murders in the city this month. Despite the announcement, some residents were still uneasy.

“We have every reason to be concerned, because we live here,” Kerry Willingham, a Perris resident, said. “I don’t want to be caught up in anything like that.”

According to Bianco, the killings appeared to be done execution-style and investigators were looking into the possibility that they were cartel-related.

The three men — 50-year-old Jaime Covarrubias Espindola, 38-year-old Jose Maria Aguilar-Espejel and 28-year-old Rodrigo Aguilar-Espejel — were all killed next to the Perris Valley Cemetery grave bearing the name of Uver Hernandez Castaneda, a local man who was killed in Mexico in a reported cartel-related hit.

Bianco also said that the department had received several tips in connection with the killings and deputies were working to try to track down the person responsible.

“To dispel any rumors, we do not have a serial killer on the loose in the area of Perris,” Bianco said. “They are isolated incidents with specific facts of their own and, at this time, we do not believe they are related in any way, shape or form.”

Perris Mayor Michael Vargas also addressed the recent spike in violence in the city and said that the council would be meeting next week to address public safety and the possibility of increasing police patrols in the area.

Bianco did not immediately disclose exactly how the men were killed or how they got into the cemetery, which was closed at the time, and does have a surveillance system.