Authorities say a woman was killed and three people injured after a gunman opened fire at a synagogue in the San Diego area on the last day of Passover.
A 19-year-old resident of San Diego, identified as John Earnest, is being questioned in custody, law enforcement officials said at a press conference on Saturday.
San Diego County Sheriff William Gore said authorities are looking at the suspect’s online activity as part of their investigation, as well as working to determine the authenticity of an online manifesto that expressed hatred against Jews.
WATCH: 1 dead, 3 injured in San Diego County synagogue shooting
They are also investigating whether the same man could be connected to a recent arson at a mosque.
Officers were called to the Chabad of Poway synagogue in Poway, Calif., just before 11:30 a.m. PT. The gunman fired on the worshippers with an AR-type assault weapon, Gore said.
An unnamed witness interviewed by NBC said the shooter wasn’t heard screaming or talking during the attack.
“He was just focused to kill. You saw the hate and the murder in his eyes.”
The victim, described as an older woman, has not been identified. The three others who were injured — a girl and two men — are in stable condition, Gore told reporters.
“My understanding is the rabbi was one of the individuals that was injured in the shooting,” he later said.
As the shooter was leaving the synagogue, an off-duty border patrol guard fired at him unsuccessfully.
Earnest was later arrested by a San Diego police officer. Earnest himself had placed a 911 call, authorities said.
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At a rally in Green Bay, Wis., U.S. President Donald Trump expressed condolences and support for the victims and the Jewish community, saying anti-Semitism “must be defeated.”
“The strength of our nation is found in the heart of our people, so true,” he said. “Tonight, America’s heart is with the victims of the horrific synagogue shooting in Poway, California.”
He also praised the efforts of the agent who sprung into action.
Steve Vaus, the mayor of Poway, expressed thoughts and prayers for the victims and their families.
“We will walk through this tragedy with our arms around each other,” he said.
He earlier told CNN that he doesn’t know anything about the person in custody but has heard it was “definitely someone with hate in their heart, hate towards our Jewish community.”
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In addition to occurring on the final day of the week-long Passover holiday, the attack took place exactly six months since a shooter at a Pittsburgh synagogue killed 11 people.
Robert Bowers, a truck driver who authorities say expressed hatred of Jews, has been charged in the Oct. 27 shooting, the deadliest anti-Semitic attack in U.S. history. He has pleaded not guilty.
A spokesperson for the Tree of Life synagogue said they were heartbroken, appalled and outraged to learn of Saturday’s shooting.
“We know first-hand the fear, anguish and healing process such an atrocity causes, and our hearts are with the afflicted San Diego families and their congregation,” a statement to media outlets said.
–With files from the Associated Press