For the dozens of Hasidic Jewish families who had settled in Jersey City over the past few years, the JC Kosher Supermarket served as a community hub.

It was the sole kosher grocery store in the area, stocking Kedem grape juice, canned vegetables and candy. The store’s popular deli counter was run by a young couple — among the first to relocate to Jersey City from the Satmar Hasidic neighborhood of Williamsburg, Brooklyn, in search of more affordable housing and a bit of open space.

The couple, Leah Mindel Ferencz, 33, and Moishe Duvid Ferencz, owned the store together. Mrs. Ferencz would stay behind when her husband ducked out to pray at the small synagogue next door each day at around lunch time.

It was at precisely such a moment on Tuesday afternoon, Mr. Ferencz’s mother said, when two people wielding guns rushed toward the store and began firing.