The incident happened at the Mira Bella Apartments on Marina Pointe Drive. The boy, identified as 4-year-old Niko Laurie, landed on a walkway below the apartment.
He was rushed to UCLA Medical Center, where he was pronounced dead at 2:44 a.m. Monday.
LAPD Sgt. Kevin Lowe says the boy fell from a bunk bed next to a window while playing a game with friends. The boy landed on concrete.
According to police, the boy's stepmother and a friend sat talking in the other room a very short distance away, and it took a split second for him to fall out of his bedroom window.
Investigators say no criminal charges will be filed, but authorities want the painful loss to be a reminder to parents to always be aware of placing furniture next to open windows and other environmental hazards - and to always watch your children.
