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

A shooting that erupted at a restaurant in Glendale, Arizona, killed three people and injured five others, authorities said.

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.