NEW YORK (JTA/The Jewish Week) — Just three weeks after terrorists killed four worshipers in a Jerusalem synagogue, a man entered a Brooklyn shul and stabbed a 22-year-old Israeli student.

New York police officers fatally shot the 49-year-old assailant, who reportedly shouted “Kill the Jews.”

At a press conference Tuesday, New York City Police Commissioner William Bratton said there is “no indication” the assailant, identified as Calvin Peters, was connected to a terrorist group. The Tuesday morning attack is being investigated as a hate crime.

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The stabbing, at the headquarters of the Chabad-Lubavitch movement in Crown Heights, highlighted the vulnerability of many large yeshivas and synagogues, particularly haredi Orthodox ones, which are often open 24 hours a day to accommodate students who end their learning or worship late at night or begin early in the morning.

The attack has prompted calls by security officials for an easing of these open-door policies, which can make schools and shuls inviting targets. While no one is suggesting airport-style searches at Jewish buildings, security experts are pointing to the need for more oversight over who comes in.

“Our goal is not to turn Jewish institutions into armed camps. Our goal is to ensure that people are trained to respond to a crisis, to be able to identify suspicious behavior,” said Paul Goldenberg, the national director of Secure Community Network, a national organization that helps coordinate security measures for the Jewish community.

Within hours of the attack, he said, his organization received requests for security briefings from several schools and synagogues.

Rabbi Chaim Landa, a Chabad spokesperson, said “ongoing” discussions are taking place with the New York Police Department. The Lubavitch headquarters building, at 770 Eastern Parkway, houses administrative offices, a large sanctuary and a yeshiva that is usually open around the clock.

Landa declined to discuss specific security measures or likely changes at the building, but said, “It’s something we’re going to look at. If it is necessary, it’s something we will improve.”

Goldenberg said representatives of local Jewish organizations that deal with security matters declined to name other yeshivas or synagogues with problematic open-door policies, for fear of identifying possible future targets, but said they will encourage these institutions to strengthen their security measures in the wake of this week’s attack.

He said the Lubavitch headquarters has “a very, very comprehensive [security] program,” but could not explain how the assailant gained access to the building.

Because of the building’s prominence, NYPD officers are usually stationed near the entrance.

The victim, Levi Rosenblat, from the West Bank settlement of Beitar Ilit, was taken by ambulance to Kings County Hospital. As of Tuesday afternoon, he was in an induced coma because of bleeding in the brain, according to a local news website. At the time of the attack, he was sitting at a table studying, according to Chabad sources.

While most major Jewish institutions have strengthened their security procedures in recent decades, as threats to and attacks on Jewish sites in the New York area have increased, some large haredi Orthodox institutions have maintained open-door policies. Goldenberg said he has encouraged Orthodox institutions to increase their security profile.

Houses of worship and schools, once considered off-limits for attacks, “are now considered soft targets … places of opportunity” by Islamic terrorists, neo-Nazis and others, Goldenberg said.

In the aftermath of Israel’s campaign against Hamas in Gaza this summer, attacks on American Jewish institutions are likely to increase, Goldenberg said.

“We have seen the institutions become lightning rods for those who want to voice negative opinions about the State of Israel,” he said.

“The shuls and yeshivos I’m familiar with have at least some security devices (e.g. cameras, alarms) and are locked at night,” Rabbi Avi Shafran, a spokesman for Agudath Israel of America, said in an email. “But the nature of such attacks is that they can’t really be prevented entirely by any such means. Even during daylight, an intruder bent on violence can walk into a shul or yeshiva no less than into a supermarket or school or church or mosque. And there have been attacks in schools even where there were guards present.”

Allen Fagin, executive vice president of the Orthodox Union, said his organization will recommend that Jewish institutions apply for funding from the Department of Homeland Security Nonprofit Security Grant Program.

Evan Bernstein, the Anti-Defamation League’s New York regional director, called the attack “a call to action for Jewish institutions across the United States to realize that these kinds of incidents can be prevented” with proper security training.

David Pollock, associate executive director of New York’s Jewish Community Relations Council, said, “Our general advice is that no unauthorized person should enter the premises — there are bad people out there. We’ve been telling [Jewish institutions] that for years.”

“We are very grateful to the police for their quick response and are working closely with the authorities in their ongoing investigation,” Rabbi Motti Seligson, a Chabad spokesman, said in a statement. “We continue to pray for the young man.”