A quick look through the S.F.-based Jewish Community Federation’s Resource guide shows the Bay Area to be home to 109 synagogues, 10 Jewish community centers, three regional federation offices and a variety of smaller organizations. It is truly a culturally rich Jewish environment.

To anti-Semites, jihadis and racists, it also could be a target-rich environment — especially with tensions running high over the situation in Gaza. In fact, a host of jihadi organizations have vowed to kill Jews on American soil.

Our community needs to take steps to avoid a tragedy like that at the Mumbai Chabad house. The Anti-Defamation League, the Department of Homeland Security and state and local law enforcement agencies already publish security manuals and videos, hold conferences and stage exercises on institutional security. Their most frequently recommended response to an armed intruder is to lock down the facility, keep the intruder under observation and call the police. But, sadly, this strategy has proven ineffective — and deadly.

After the Northern Illinois University shooting, the university president and chief of police congratulated themselves on the success of their “rapid response” plan that made it possible for the police to reach the shooting site in less than 20 minutes. The plan’s only flaw was that the police arrived about 18 minutes after the shooter had finished. In the first two minutes of the attack, the shooter had fired 48 pistol rounds and five shotgun rounds, killed five people, wounded 24 others and then killed himself. The same chronology characterizes almost all mass shooting incidents in the United States — when police are needed in seconds, they are minutes away.

All mass shootings in the U.S. have been by disturbed, possibly delusional people with little or no firearm training. A Mumbai terrorist, moderately well trained and not perceptually impaired, could have killed two to three times as many victims. Two or three shooters trained to American, European or Israeli commando standards would do far more.

Repeated experience has shown that the only effective defense against an armed incursion is intervention by people on site carrying concealed weapons. The police cannot get there in time to intervene, and the open carry of weapons marks the guardian as the terrorist’s first target.

Case in point: the New Life Church in Colorado Springs has a security patrol of congregants, some of whom are licensed to carry a concealed pistol. A shooter entered the church parking lot, killed two sisters, and wounded three others. When the shooter tried to enter the building, he was wounded by a pistol shot from one of the armed congregants. He then committed suicide with his own gun. Had there been no one barring the way to the sanctuary of this mega-church, he could have committed a mass murder of considerable magnitude.

The guardians of the congregation should themselves be congregants trained in screening and in close quarters combat shooting. Commercial guards and off-duty police cannot be as accurate in screening people.

This is not like most police work — it is close quarters combat shooting, something for which police (other than SWAT team members) receive almost no training. A person with good vision and mobility can be trained to an adequate standard in between 40 and 80 hours, followed by monthly or bimonthly practice. It is not a trivial training commitment, but this is not a trivial job.

Anyone who can qualify for a concealed carry permit is morally qualified to train as an armed guardian. People with carry permits have a negligible crime and accident rate — Florida has revoked only 0.01 percent of its 1.36 million concealed carry permits, mostly for the accidental carrying of a handgun into an airport terminal.

After every tragedy comes the question, “What could we have done to prevent or mitigate this?” To say “we knew it might come, but we chose not to prepare” will not do. If we are to make use of all available means to mitigate the negligible risk of fire, should we not do the same to mitigate the negligible risk of armed attack?

Remember “artificial respiration”? We were taught to pull on a drowned person’s arms or to push on their backs to get them to breathe. Researchers soon learned that artificial respiration had exactly no effect on blood oxygen levels. They also knew that since biblical times, people were revived by air blown into their mouth to inflate their lungs.

So why did they substitute something that did not work for something that did? Because in the late 19th century, when artificial respiration was invented, blowing into another man’s mouth was considered socially unacceptable and “yucky.”

Having concealed guns in shul may be uncomfortable, but when the rare situation arises, it is the only thing that will work.

Richard C. Roistacher of Belmont is a former Special Forces soldier, a licensed armed security officer, and an NRA certified instructor in pistol shooting and in personal protection in the home. He has had more than 400 hours of formal training in defensive combat shooting.