It happened on an empty R train at the Forest Hills-71 Avenue subway station on Saturday.
Authorities say the six people got inside the train before briefly operating it and then vandalizing some of the glass panels on the train's camera before running off.
On Wednesday, MTA Chair and CEO Janno Lieber said multiple failures led to the six suspects moving the unoccupied R train from a storage yard.
"What happened here is not acceptable, failure of the security in the layup area, as far as I'm concerned, I'm burned about this, for the riders and all of us," Lieber said.
Anyone with information regarding is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
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