At least nine people were shot on Sunday night when gunfire tore through an Arizona restaurant where a Cinco de Mayo celebration was being held.

Panic erupted around 7:45pm on Sunday night at a Glendale steakhouse, near the intersection of Glendale and Grand avenues, where stunned witnesses reported a barrage of gunshots by the restaurant.

Police received several frantic 911 calls as the scene at El Camarón Gigante descended into chaos.

The venue was holding a family-friendly Cinco de Mayo party with dozens of people of all ages present.

One eyewitness reported hearing more than 20 shots with the shooting carrying on for 15 to 20 seconds before a further 10 shots rang out 30 seconds later.

At a tense press briefing around 9pm, Glendale Police Public Information Officer Moroni Mendez described a scene of confusion and urgency.

While initial reports suggest there could be up to nine victims, Mendez stopped short of confirming the exact number, citing the fluid and ongoing nature of the investigation.

‘I heard people yelling out names. There was a man on the ground and it didn’t look like he made it,’ Lupe Rodriguez, a bystander who ran to safety, said to AZFamily. ‘His father was yelling out his name. It was pretty bad.’