The Montgomery County Fire Marshal's Office says the boy was with his 7-year-old brother in the backyard, standing near a trash fire when the can erupted.
The 3-year-old child was hit by flames, which caused second and third-degree burns over 60 percent of his body.
Investigators say the 7-year-old called 911 to get help for his brother.
We do not know where the boys' parents were at the time of the incident.