Which two major characters are implied to have died at the beginning of chapter 2?

The two major characters that are implied to be facing certain death are Elie Wiesel's mother and youngest sister, Tzipora. However, this implication is present at the beginning of chapter 3.
In chapter 2, Mrs. Schachter's eerie screaming unnerves her fellow Jews. At Auschwitz, it is suggested that Mrs. Schachter be moved to a hospital car. The German officer who hears the request replied with an ominous "Patience...patience. She'll be taken there soon." It is not difficult to decipher what the officer means. Jews like Mrs. Schachter were ultimately headed to the crematoria. However, at this point, there is no suggestion or implication that Mrs. Shachter has died.
At the beginning of chapter 3, we are given this information:

Tzipora was holding Mother's hand. I saw them walking farther and farther away; Mother was stroking my sister's blond hair, as if to protect her. And I walked on with my father, with the men. I didn't know that this was the moment in time and the place where I was leaving my mother and Tzipora forever.

According to the paragraph, there is no suggestion that Elie's mother and little sister have died. However, there is the implication that both are going to their deaths. In the preface to the book, Wiesel confirms that his mother and youngest sister were sent to their deaths on the first night of their arrival at Auschwitz.

Or the discovery of a demented and glacial universe where to be inhuman was human, where disciplined, educated men in uniform came to kill, and innocent children and weary old men came to die? Or the countless separations on a single fiery night, the tearing apart of entire families, entire communities? Or, incredibly, the vanishing of a beautiful, well-behaved little Jewish girl with golden hair and a sad smile, murdered with her mother the very night of their arrival? [from the preface to Night]

The culling processes at the camps were brutal: only able-bodied men and women were allowed to survive for a time. Babies, young children (like Tzipora), and the elderly were summarily executed upon arrival at camp. So, the two major characters that are implied to be facing certain death at the beginning of chapter 3 are Elie's mother and youngest sister, Tzipora.