A 5-year-old boy wandered out of a kindergarten class in Manhattan on Thursday afternoon and was later found alone on a subway station platform, police said.

The boy walked out of PS 11 on West 23rd Street in Chelsea at about 12:15 p.m. and walked up 8th Avenue to the C and E train platform at 23rd Street, authorities said.

He likely ducked under the subway turnstile on his way down into the train station, cops said.

A good Samaritan spotted the boy alone on the platform and called police at about 12:30 p.m., authorities said. Cops contacted his school and reunited him with his mother.

The Department of Education did not immediately return a request for comment, but told ABC 7 in a statement: “This serious incident was immediately reported to NYPD and the student was swiftly and safely found. We have referred this for investigation and will ensure appropriate follow-up action.”