He was playing with another child, and his father was home at the time.
The father performed CPR until help arrived, and the child was rushed to Stony Brook Hospital in critical condition.
Investigators said two boys, the other a 4-year-old, were inside a house playing when the younger one got tangled up in the cord of the blind.
It was not immediately known how long the boy was tangled or how long he was without oxygen.
