Police said a 6-year-old child who fell down an elevator shaft at a Grand Concourse building Thursday afternoon is in critical condition.

It's still unclear how many stories he fell, but police said he lives on the first floor of 1235 Grand Concourse just before 1 p.m.

Segundo Campoverde, the boy's grandfather, said he is just praying that his grandson survives after undergoing surgery for a fractured skull.

He told News 12 that his grandson has special needs and is known for trying to sneak out of the apartment. He said they installed at least three locks on the door, but that the young boy managed to open all of them and escape.

Campoverde said he was in his bedroom and the boy's babysitter was in the bathroom. Within seconds, the child undid the locks and ran out.

Campoverde said he immediately ran after him but he was so fast so he could not find him.

Police said surveillance footage shows him walking through the apartment building and up the stairs before he makes it to the sixth floor, which is where the roof is.

Once on the roof, police said the young boy got inside the elevator room where there was a gap between the wall and grated floor -- a space just big enough for him to slip through and fall down the shaft. He landed on top of the elevator.

They said it's unclear what floor the elevator was on, so they could not determine how far he fell. The FDNY later found him unconscious on top of the elevator in the basement before they rushed him to Harlem Hospital.

Neighbors say they are familiar with the boy and that they often see him roaming throughout the building. Others who live nearby say they are disturbed and that someone must be held accountable.

The Department of Buildings was at the scene of the incident and said investigators looked into whether there were any incompliant conditions that would have allowed the child to gain access to the elevator. It also said that it issued a cease-use order on the elevator for the time being and is working with the owner's elevator service company to conduct a full inspection.

News 12 tried to reach the building's superintendent to learn more about how the child got through doors that are supposed be locked but has not heard back.