Two children and their grandmother were killed Thursday night in a fire in Edogawa Ward, Tokyo, police and firefighters said.
Two homes were destroyed and six were damaged in the blaze.
The fire broke out at around 11 p.m. in the home of Yoshikazu Miyamoto, 35, firefighters said Friday. Those killed were identified as Miyamoto's sons, Yuki, 2, and Shota, 5, and his mother-in-law, Hamako Kikuchi, 70.
Miyamoto, who was sleeping on the second floor, helped his 7-year-old daughter, Manami, escape onto the balcony of a neighboring house. He then jumped to the ground, doused himself with water and ran back into the blazing house to rescue his other children. He found his 4-year-old son, Kazuto, and father-in-law, Hiroshi Kikuchi, 72, on the first floor and led them outside.
Miyamoto's wife, Mitsuko, 33, was not at home at the time, according to police.
The two surviving children and the father-in-law suffered smoke inhalation, police said. Miyamoto sustained slight injuries to his hands.
Two 13-year-old girls from the neighborhood who helped Miyamoto rescue Kazuto were also injured, police said. They were all taken to a hospital.
Police are investigating the cause of the fire.