A fight between a group of people with a history of “bad blood” escalated Sunday night into a shooting during a crowded event outside a suburban Phoenix restaurant, leaving three dead including a teenager and five others injured,

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.

NBC affiliate KPNX of Phoenix reported that the restaurant El Camarón Gigante was holding a Cinco de Mayo party at the time.