Sioux City police say in a news release that Misael Gonzales Velasquez died at Saint Elizabeth Regional Burn and Wound Center in Lincoln around 3 a.m. Monday. He was flown there Sunday after initial treatment at a Sioux City hospital.
Firetrucks were sent to the building around 3:40 a.m. Sunday, and firefighters say the flames filled an upstairs apartment where they found the boy.
The fire cause is being investigated. Authorities say the blaze displaced 13 building occupants.