NEW YORK (CBSNewYork) – An 8-year-old boy who walked out from his Brooklyn charter school was found wandering on the J train subway tracks Tuesday.

The boy was reported missing at around 12:20 p.m. Tuesday after walking out of the Brooklyn Excelsior Charter School in Bedford-Stuyvesant.

He was found about 20 minutes later walking on the elevated tracks of the J train subway at the Halsey Street station, about 10 blocks away. A bystander was able to remove the boy from the tracks before a train arrived.

Transit police were alerted and Emergency Medical Services personnel took him to Woodhull Hospital, where he was evaluated and eventually released to his family.

Parents, caregivers and students that CBS2’s Elise Finch spoke to said they were baffled as to how this happened.

“That’s very surprising, because I know the security at this school is extremely good,” parent Nazeefa Sinclair said.

“If anybody can walk out, anybody can walk in,” another woman said.

“This is a good school. There’s usually people out here,” a man added.

The school’s principal told CBS2 in a statement that a staff member saw the boy leave the building and immediately followed him. It’s unclear how he made it all the way to the train station.

“When staff saw a student exit our building during school hours Tuesday morning, they immediately followed the student. Our staff quickly enlisted police to assist in locating the student, who was found shortly afterward,” Brooklyn Excelsior Charter School Principal Dr. Christopher Petty said in a statement.

“Children can get out of school anywhere,” grandmother Carla Ramoutar said. “I worked for Headstart for many years.”

“I wouldn’t expect an 8-year-old to be on the tracks. I would probably try to help too,” Jamaica resident Stacey Ann Francis said.

The school said it is reviewing the incident.

“We appreciate the quick actions of the New York Police in helping to keep our student safe,”Know that we are reviewing this incident and will take appropriate steps to ensure we continue to provide a safe, secure learning environment for our students,” the statement continued.