The incident happened just west of Grant Avenue. LIRR crews were working to repair 500 feet of cable that was damaged.
The work caused delays of up to 15 minutes in both directions on the Montauk Branch east of Babylon. Trains were moving at slower speeds on the branch.
It's not clear how much if any cable was actually stolen.
In addition to the train delays, gates at six train crossings locked in the down position as a failsafe when the wires were damaged. MTA Police were directing traffic at those crossings.
Repair work was finished at around 9pm. Service is back to normal on the Montauk Branch after earlier rush hour delays.
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