During Minha on a Ta’anit Sibur (public fast day), such as Tisha B’Ab, we read from the Torah the section of "Vayehal Moshe," and the Hazan adds the Beracha of "Anenu" in his repetition of the Amida, between the Berachot of "Go’el Yisrael" and "Refa’enu."

If, however, most of the people in the Minyan at Minha are not fasting, and there are fewer than six men fasting, then the Torah is not read, and the Hazan does not add the Beracha of "Anenu" in the repetition of the Amida. If, in such a case, when the Hazan begins the Beracha of "Refa’enu" more people who were observing the fast entered the synagogue, such that there were now at least six men who were fasting, then he should go back and recite "Anenu." If the people arrived only after the Hazan completed the Beracha of "Rofe Holeh Amo Yisrael," then he can no longer go back to recite "Anenu" as a separate Beracha, and he should instead insert "Anenu" in the Beracha of "Shema Kolenu." They then read the section of "Va’yehal" after the repetition of the Amida.