Metro-North Hudson Line District Superintendent James Rickard, rail traffic controller Peter Gloistein, and MTA police officers Graziano and Connolly all came together to save the dog.
Milly was spotted two miles north of Beacon.
Glosistein was able to slow down rail traffic so that Rickard and the officers could catch her.
"We stopped and she ran by us. We had to stop and then go chase her northbound," Officer Connolly said.
"She was a little scared at first, but once we pulled up, I opened the door and called her and she hopped right in the car," Rickard said.
"You could tell she almost wanted us to help," Officer Graziano said.
Rickard's wife went on Facebook to find Milly's owner.
Milly was reunited with her grateful owner at a nearby Dunkin Donuts.
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