By Soo-hyang Choi, Daewoung Kim and Hongji Kim SEOUL (Reuters) – Shocked family members collected bodies, parents searched for children and a country sought answers on Sunday after at least 153 people were crushed to death when a crowd in South Korea surged in an alleyway during Halloween festivities. President Yoon Suk-yeol declared a period of national mourning and designated Seoul’s popular Itaewon district a disaster zone after the Saturday night disaster. “This news came like a bolt from the blue sky,” said a father who burst into tears as he collected his daughter’s body from a morgue in…