One person has been killed and three others hospitalised after a gunman opened fire at a synagogue outside San Diego.
Worshippers were celebrating the last day of Passover when the suspect, thought to be heavily armed and wearing tactical gear, stormed the Chabad of Poway, California, around 11.30am local time today.
There is now no known threat after a man was detained after the incident.
But authorities have boosted patrols at places of worship as a precaution, San Diego Police Chief David Nisleit said.
Poway Major Steve Vaus told US media outlet CNN that one person had lost their life in the shooting.
He also wrote on Twitter: "Hate has no place in ANY community... least of all Poway.
"We will put our arms around each other and walk through this tragedy as the family we have always been and always will be."
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The incident came exactly six months after a shooting at a Pittsburgh synagogue killed 11 people in the deadliest attack on Jews in US history.
Officials said San Diego County deputies were called just before 11.30am.
A handful of police cars were parked outside the synagogue in the city of Poway, just over 20 miles north of San Diego.
Crime tape surrounded the street in front of the building.
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Passover began on April 19 and ends on Saturday.
In Pittsburgh, a truck driver who authorities say expressed hatred of Jews has been charged in the October 27 rampage at the Tree of Life synagogue.
He has pleaded not guilty.
