It has long been a Jewish tradition to embrace the stranger, but after Saturday's shooting at a California synagogue, Jewish houses of worship appear to be putting hospitality aside in favor of security.

In the aftermath of two fatal synagogue attacks within a six-month span, more Jewish centers are locking their doors, stationing armed guards at their entrances and urging members to be wary of newcomers.

And some congregants — aiming to fight back — are flocking to gun ranges.

Saturday's attack, in which a 19-year-old gunman opened fire at the Chabad of Poway synagogue, killing one and injuring three others, sent shock waves through the Jewish community. Six months ago, 11 people were killed in a similar attack at a Pittsburgh synagogue.

Other houses of worship have also been targeted: On Easter Sunday, more than 250 people were killed in bombings of churches in Sri Lanka, and 50 people were killed in an attack on two mosques in New Zealand on March 15.

The spate of hate-fueled violence gives deeper meaning to this week's observance of Yom Hashoah, Holocaust Remembrance Day, which commemorates the 6 million Jews killed by Nazis during World War II.

The synagogue shootings are part of an ongoing pattern of hate incidents that have soared across the country in recent years. An Anti-Defamation League report released Tuesday documented a dramatic increase in anti-Semitic incidents in 2018, when violent assaults against Jews more than doubled over the previous year.

New Jersey ranked third in the nation in anti-Semitic incidents in 2018, after California and New York, according to the ADL.

In the aftermath of the recent shooting, synagogues nationally have renewed their focus on security.

Among them is the Chabad of Hackensack, which was vandalized with swastikas several years ago. Rabbi Mendy Kaminker said his facility is already armed with a security system but has been reviewing additional security measures with local police. "We want to make sure we use the best practices to make our congregants feel safe," he said, declining to divulge any plans.

Temple Emanu-El in Closter has multiple uniformed and undercover armed guards at the facility around the clock. Rabbi David-Seth Kirshner is reevaluating his synagogue's safety efforts after the recent shooting, but feels wary about taking additional steps.

"I hope our places of worship don't become fortresses," he said. "It will hurt our enterprise in the end."

Jason Friedman, executive director of the Community Security Service, a California-based nonprofit that has been assisting Jewish institutions with security matters since 2007, said his group has trained more than 4,000 Jewish volunteers across the nation in how to keep their own synagogues safe. He hopes his ranks will continue to swell.

The CSS focuses on preventive measures, training community members to look out for suspicious people, behaviors and vehicles. "The main part of staying safe is preventing a bad actor from getting in. That's what we want every synagogue in the country to be able to do," Friedman said.

Community members trained by CSS have already thwarted several incidents, including one in which someone attempted to impersonate a police officer and storm a New York synagogue.

There is no one-size-fits-all approach to security, as every community is different, observed Evan Bernstein, New York/New Jersey regional director of the Anti-Defamation League. "Whenever these horrific acts happen, we hope synagogues will look at their security protocols and have the experts come in and offer intel so they can make the best security decisions for themselves," he said.

With violence becoming more common at houses of worship, businesses that offer training and security are in demand.

Area gun ranges, which offer firearms courses, training sessions for active shooter scenarios, and free security evaluations, say they've been inundated with calls since the Pittsburgh shooting.

"I hate to say it, but it's good for business," mused Jimmy Grammenos, director of training at Gun for Hire in Woodland Park. "We get a lot more calls after these incidents."

Many of the inquiries are from worshipers who fear their religious centers will be targeted next and want to be prepared. Grammenos said people are often surprised when they discover how complicated the process is to obtain a gun in New Jersey and that it can take months. In the meantime, he suggests taser or mace training.

Rick Friedman, the CEO of RTSP shooting range in Union and Randolph, has also seen increased interest recently in training courses and security evaluations.

Friedman, an auxiliary police officer who regularly guards synagogues in New Jersey, said the reason fewer lives were lost in the California shooting than in Pittsburgh was because an off-duty border patrol agent in the synagogue stopped the gunman.

The agent, Jonathan Morales, chased and shot at the gunman's car, according to news reports.

"All the laws in the world can't end hate crimes, but we need to meet them head on when they do occur," said Friedman, who advocates relaxing New Jersey's gun laws to make it easier for people to defend themselves outside of their homes.

"There's not a house of worship in the country that doesn't need protection," he said. "The cost-effective thing is to legally and responsibly train a select few congregants that feel comfortable."

Eli Davidovics, co-owner of Hackensack-based Six Point Security, a company that offers training programs and armed guards, said business has been brisk. Some people have told him they are afraid to attend services, while others say they want to fightback against attackers. "People want to do something, and that's great as long as it's done logically," he said.

"There shouldn't be a knee-jerk reaction every time something occurs," Davidovics said. "You have to look at your security strategically."

That means, he said, assessing a facility for vulnerabilities, conducting training programs for congregants and hiring vetted armed guards who understand the community.

Indeed, even Rabbi Yisroel Goldstein of the Chabad of Poway revealed that the deadly attack could have been prevented had his synagogue been able to afford armed security guards.

"Unfortunately, everyone is agitated and nervous right now," Davidovics said. "But if you are doing everything right, the deterrent to any threat is tremendous."