It had been a joyful reunion lasting late into the August afternoon. Occasionally, I would lean back and tune out the lively conversations just to smile, over wine bottles andI listened with pleasure to the variety of languages and dialects half-filled glasses, at the seven people sitting alongside me. Having lived and worked in Spain as a young teacher, I periodically return for visits. This particular trip, I had shopped in villages nestled in scenic mountains and sat leisurely on my friend’s terrace, which offered a magnificent view of Barcelona and the foothills of the Pyrenees, but nothing compared to this lunch with my former colleagues of 15 years.

It was nearly 5 p.m. when we left Restaurant Maccabi. It’s one of the new kosher eateries mushrooming in the Barcelona area in the popular tourist section known as Las Ramblas. Two of my colleagues and I decided to extend our visit and take a stroll down the wide, tree-lined esplanade. Teeming with colors and scents, Las Ramblas was bustling with shops and kiosks, markets, cafes and theaters, filled with the animated chatter of people from all over the world. I listened with pleasure to the variety of languages and dialects. As a now-retired high school Spanish teacher, I always found the intermingling of human speech fascinating.

Without warning, the pleasant afternoon was rent with something that sounded like multiple explosions and bullets, punctuated by screams of terror. I turned. A white van raced down the sidewalk; people scrambled to get out of its way. A hundred yards from me, it deliberately zigzagged to obliterate a kiosk. This was a terrorist attack, I thought, like the one on London Bridge just two months ago. For a moment, I stood in frozen disbelief—and then started running with all my might. A voice inside said not to look back—to keep running. I never moved so fast, yet it felt like slow motion. At the same time, I could feel someone or something pulling me to safety, pulling me with such force that it seemed I was taking huge leaps, somehow flying over the tangled chaos of people and debris until I found myself inside a Spanish-style clothing shop called Desigual.

Inside, people were crouching beneath racks of clothes and display cases. With a pang, I realized that my colleagues were not behind me, though I couldn’t think about that now. What was vital at this moment was finding a place to hide. Catching site of a counter, I plunged behind it to find several other women already huddled there. One of them, a young Spanish college student, was crying. Working a summer job at a nearby shoe store, she had been running an errand when she got caught in the attack. The other, a British woman, had been separated from her 15-year-old daughter. She was still shaking even after receiving a text that her daughter had safely escaped to another store.

It was then that I decided to text my own daughter in Illinois. Pulling out my phone, I was stunned to find that what had seemed like hours since the attack had been a mere six minutes.

“I’m OK. Tell grandma and grandpa I’m OK,” I texted.

“What’s going on?” she immediately responded.

“Can’t explain now. I’ll tell you in a bit.”

Next, I contacted my colleagues. To my relief, one of them had actually followed me and was somewhere in the same shop. The other had run down the esplanade until police forced him into a different building. He texted that what I thought were bullets and explosions was actually the sound of bodies ricocheting off the van. He had seen them tossed in the air like so many rag dolls.

Immediately after that conversation, I received a message from a friend in Chicago bestowing her birthday blessings on me. I stared at her words—the disparity between her happy pronouncements and my current situation almost irreconcilable. But I sent back my profound gratitude to her. Blessings at this moment were a precious commodity.

The manager and shop employees had hastened to pull down the metal security gate and were now urging us, about 80 people, to go down to the lower level where it would be safer. As we filed down the stairs, I carefully observed my companions, listening intently to their various languages. Had the staff locked us in with a terrorist? We heard sirens and helicopters, but the information we could glean from our families and social-media sources was sparse and contradictory. We had no idea what was happening outside.

People milled about,Had the staff locked us in with a terrorist? tense and frightened. I came across a young woman from Estonia who had just flown into Barcelona a few hours earlier, dropped off her luggage, and had come to Las Ramblas for an early supper when she had been caught in the attack. Visibly traumatized, she had witnessed multiple horrors before running to safety. I spoke with her for a while. Then I turned to two very young Italian girls who were crying. Between my Spanish and their Italian, I was able to calm them.

When I assured the girls that everything was going to work out, I realized that it was something I wholeheartedly believed. It seemed that the chassidus I had been learning all these years had coalesced and become a lifeboat for me. I thought of the sixth Chabad Rebbe—Rabbi Yosef Yitzchak Schneersohn, of righteous memory—looking down the barrel of a Soviet pistol, coolly saying that the officer holding it had one world and many gods while he had many worlds and one G‑d. I thought about our Rebbe—Rabbi Menachem M. Schneerson, of righteous memory—stating unequivocally that the midda of good (chesed) is 500 times more powerful than its opposite. Finding a quiet corner, I prayed Mincha and then returned to what I thought the Rebbe would want me to do: continue helping people here, and by doing so, spread a light that had 500 times the strength of those who had just wreaked havoc on so many innocent victims.

The waiting seemed interminable. Finally, the manager received word from police officers that they were coming to evacuate the store. Nearly three and a half hours after the attack began, they arrived, marching in double file, their helmets, bulletproof vests and machine guns almost as frightening as the encounter with the van. With military precision, they escorted us out of the building and stood us against a wall facing Las Ramblas. The busy, festive thoroughfare now looked like a military zone—roped off, deserted, deadly quiet.

We were led to Plaza Catalunya, the endpoint of Las Ramblas, where each of us was filmed, questioned by the police and asked to show identification. While we waited to be processed, Christina, the young Spanish college student I had first met, said that her parents were waiting to pick her up but since she had no identification—her purse was left behind in the store where she worked—she was frightened about being detained. I offered to accompany her, but when she was taken away for further interrogation, I wasn’t allowed to follow.

After my release, I walked a few blocks beyond the cordoned-off downtown area where a friend was waiting to drive me back to her home. It was a long drive. There were police blockades throughout Barcelona.

During the next few days, I tried to understand and integrate what had happened to me and to so many other people. I texted my rabbi in Chicago. He advised me, among other things, to recite Tehillim (Psalms), especially chapter 100. I started reciting it wherever I went. Armed with these powerful words, I decided to return to Las Ramblas. The thought of going back there triggered such anxiety that I knew if I didn’t do it soon, I never would.

The shops were again open and the sidewalks crowded, but a profound change had taken place. Everywhere, there were now makeshift memorials with people huddling around them, subdued and introspective, their heads bowed. Escorted by a friend (I couldn’t have gone alone), I retraced my steps from that terrible day, stopping to recite chapter 100 at various locations. I prayed, numbed and oddly removed, flooded with too many emotions to feel anything.

During those few days after the attack, I kept thinking of Christina. She had been so frightened when the police had separated her from the rest of us. I decided, while we were on Las Ramblas, to see if she had returned to work. Again, an invisible door opened wide: My friend and I found her in the second shoe store we investigated. I was so happy and relieved to see her. We hugged—comrades who had been through the war together—and exchanged email addresses.

That evening, I received a message from her: “Thank you for everything, I will never forget you. I don’t know how you did it, but you were able to calm me down [when] I was having a panic attack. It’s at times like these that one realizes that there aren’t only people who do bad things, but there are also good people that help each other in these bad times. You can’t even imagine how much you helped me . . . Truly, I will always be grateful to you.”

In her words, I felt a reverberation of the Rebbe’s message. I re-read the email. Then, for the first time, I was able to cry.

On the day of the attack, when I finally had a moment to send a detailed text to my daughter, II had not been physically touched at all told her it had been people who had pulled me out of the van’s trajectory and into the shop. But later at home in Chicago, thinking back, I realized that no one had actually done that. I had not been physically touched at all. A friend suggested that perhaps it was angels, but on reflection, I feel it was something deeper. I think it was all the prayers I had ever said that had saved me—every Amidah, every Aleinu, every psalm. The might contained in those holy words, in those very letters, surrounded and protected me, and carried me to safety.

A total of 16 people were killed during that attack and more than 100 injured—Spanish citizens, Americans, innocent people from all over the world. In the face of such indiscriminate evil, it would be easy to feel overwhelmed and helpless. But on that August afternoon, I discovered within me weapons stronger than any speeding van: Torah and mitzvahs, prayers and the Rebbes’ teachings. I also found, in this personal arsenal of mine, a new meaning to chesed, of lovingkindness—a force more powerful than I could have ever imagined.