A man in his 30s killed three people, including a six-year-old boy, in a one-minute shooting-spree at the annual Gilroy Garlic Festival in northern California on Sunday evening before he was gunned down by police, local reports say.
At least 11 revellers injured in the shooting have been taken to two local hospitals in fair to critical condition.
On Sunday night, Gilroy police were using helicopters and canine squads to search for a second possible suspect at a creek behind Christmas Hill Park where the three-day festival was organised.
Gilroy Police Chief Scot Smithee said the shooting began at 4.51pm and the police arrived on the crime scene one minute later. The unidentified shooter was immediately shot and killed.
The suspect or suspects may have come from the creek and cut through the wire fence to avoid security before shooting in all directions making revellers flee.
Smithee said the identity of the dead gunman and his motive for the attack remain unknown.
Witnesses described the attacker as a white man in his early to mid-30s dressed in green, camouflage pants and wearing a cap and sunglasses. He was carrying an assault rifle which police seized from the crime scene along with ammunition.
In his tweet, President Donald Trump asked Gilroy residents to be careful and safe since a second suspect seemed to be on the run.
Gilroy Mayor Roland Velasco tweeted the thoughts and prayers of the local community are with the families of the victims of this senseless crime.
Expressing shock over the “horrific” incident, California Governor Gavin Newsom tweeted the city stands with the Gilroy community.
The festival was about to conclude when the shooting began. Initially, revellers thought it was some fireworks to mark the end of the three-day celebrations.
When they realised a gunman was killing or injuring people, they dropped to the ground or ran towards the fence to escape the bullets.
Smithee said it was a nightmare one hopes to never have to live.
Gilroy garlic festival attracts more than 100,000 food lovers every year.
The festival also helps raise funds for local clubs, schools and other non-profit groups.