
Police said the fire started at about 10.30pm among the patch of houses on Soi Lat Krabang 3 near Wat Sangha Raja.
Crews arrived on 10 fire engines and brought the blaze under control after two hours.
The baby boy’s charred body was found on a bed in the house where witnesses said the fire started.
House owner Yutthan Wanitphansakul, 40, said he left his seven-year-old daughter in charge of the infant while he was chatting with friends at the mouth of the soi.
He saw his daughter running from the house as it burned and tried to go in to rescue the boy, but his neighbours held him back.
Lat Krabang police chief Pol Col Sarawut Siri said the cause of the fire, which damaged homes across one rai, had yet to be determined.
The affected families would be given temporary shelter at the temple, he said.