The incident reportedly happened during the last day of the Gilroy Garlic Festival, in Sacramento. Police confirmed that there had been a number of casualties. Reports suggest it remains unclear as to how many people were potentially injured during the shooting.
NBC Bay Area said ambulance crews were told 11 people had been shot.
The festival is an annual three-day event.
Shocked people shared footage of the shooting on social media.
Loud popping sounds could be heard in the background while guests fled upon hearing the loud gun sounds.
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One woman was heard shouting in the video” “What’s going on?
“Who’d shoot up a garlic festival.
The first festival was held in 1979.
It features food, drink and live entertainment.
Organisers claim it is the “world’s greatest summer food festival”.
It was being held at the outdoor Christmas Hill Park, where weapons of any kind are prohibited, according to the event’s website.
Festival officials did not immediately respond to requests for comment.
Gilroy is about 30 miles (48 km) south of San Jose.