The fatal shooting Sunday night at a restaurant and event venue in Glendale, Arizona, was an “isolated incident that involved individuals that were known to one another,” the city manager’s office said in an update Monday.

At least three people were killed and five people were wounded in a shooting that erupted on Sunday at a restaurant in Arizona where a crowd of people was celebrating Cinco de Mayo, the police and a witness said.

Police in Glendale, Arizona, said three people are dead and five injured after a shooting at a restaurant Sunday night. No one has been arrested, but investigators believe multiple shooters were involved.