How does Mrs. Nakamura and her children spend the night prior to the bombing?

From the text:

At nearly midnight, the night before the bomb was dropped, an announcer on the city’s radio station said that about two hundred B-29s were approaching southern Honshu and advised the population of Hiroshima to evacuate to their designated “safe areas,” Mrs. Hatsuyo Nakamura, the tailor’s widow, who lived in the section called Nobori-cho and who had long had a habit of doing as she was told, got her three children—a ten-year-old boy, Toshio, an eight-year-old girl, Yaeko, and a five-year-old girl, Myeko—out of bed and dressed them and walked with them to the military area known as the East Parade Ground, on the northeast edge of the city. There she unrolled some mats and the children lay down on them. They slept until about two, when they were awakened by the roar of the planes going over Hiroshima.