The unfinished meals of fleeing customers are left on tables at an outdoor restaurant near the scene of a twin bombing at the Boston Marathon on April 16, 2013 in Boston, Massachusetts.(Spencer Platt/Getty Images)

In the moments that followed the detonation of two bombs near the finish line of the Boston Marathon yesterday, Rabbi Mayer Zarchi of Chabad Lubavitch of Boston found himself at the epicenter of chaos. The rabbi, who was handing out Jewish literature to some of the 500,000 visitors that the marathon had attracted at a tefillin stand a block away, heard the explosions and immediately recognized the sound.

“I’ve heard these kinds of noises before, and as soon as I heard it, especially after the second one, I knew what it was,” he said in a telephone interview today. “What I heard, what I smelled and the kind of wounds you saw, were all emblematic of a bomb.” He went on to add, simply, “It was terrible.”

As police started escorting shocked witnesses away from the blast scene, the rabbi began to make his way back to the Chabad House, three blocks away. Because of its proximity to Copley Square, the Chabad House quickly became a refuge for confused and terrified runners who began pouring in to make calls to their family and friends from landline phones.

“These kinds of attacks don’t discriminate,” said the rabbi, who in December performed the annual menorah lighting in Copley Square. “It rang really close to home.” Around 6 o’clock, Rabbi Zarchi went to the waiting room of Massachusetts General Hospital to comfort the families of victims and stayed for the rest of the night.