On Monday, or 7-11, at least four shootings, two of them fatal, were reported at the California 7-Eleven store.
Authorities are searching for suspects related to the three in the Los Angeles area.
It is unclear whether the suspect was linked to the 7-Eleven shooting in Riverside, a police spokesman said.
One victim in the incident, a customer in his mid -40s, remained in a “grave” condition late Monday afternoon, Riverside police spokesman Ryan Railsback said.
The suspect allegedly entered the store, robbed a clerk and shot a customer before fleeing shortly before 2 p.m., Railsback said.
The other robberies and shootings occurred in Santa Ana, Brea and La Habra from 3:20 am to 4:55 am, authorities said.
Sgt. Maria Lopez, a Santa Ana police spokeswoman, said that it’s unclear whether it “became 7-Eleven on 7/11 related to why he did that,” adding, “It’s hard for me to say.”
The company – which offers free frozen drinks Monday for “Slurpee Day” – said in a statement: “We hate the victims and their loved ones. We are gathering information about this terrible tragedy and working with local law enforcement.”
The victim in the Santa Ana shooting was found in a parking lot outside 7-Eleven after the shooting was reported at 3:20 a.m., Lopez said. The victim, who has not been identified, was shot once in the head and died at the scene, NBC Los Angeles reported.
“We don’t believe that he’s an employee,” Lopez said. “He’s probably either walking or he’s a potential customer.”
Detectives linked the suspects to other shootings after they saw security photos released by authorities in Brea, about 13 miles north, Lopez said.
In the shooting, officers responded after 4 a.m. to a report from a 7-Eleven clerk who had been fatally shot during a robbery, the police department said on Twitter. The clerk, who has not been identified, died at the scene.
“Our hearts go out to that person’s family,” Brea Police Captain Phil Rodriguez said in a briefing. “Please know we’re thinking of you.”
Additional details about the shoot were not immediately available. Rodriguez said authorities plan to warn 7-Eleven stores to take additional precautions.
In the fourth shooting in the nearby town of La Habra, officers found two people who had been shot after the robbery was reported just before 5 am, Sgt. Sumner Bohee, a police spokesman, told reporters.
The victim was taken to a hospital, he said. The circumstances are not immediately known.
“We believe that they are the same suspects” in the shoot of Brea and La Habra, Rodriguez said.
Tim Stelloh is a news reporter for NBC News Digital.