Rail travelers looked on in horror Sunday evening as a 31-year-old Waterbury woman, panicked by an approaching train, ran back and forth across the tracks at the downtown railroad station until the train struck her.

"This was a horrible tragedy," police Lt. James Perez said Monday. "An error in judgment cost this young woman her life."

Fallon Newvine of Waterbury died when she was struck by northbound Amtrak train 88 around 5:30 p.m. Sunday as she attempted to cross the tracks at the depot, Metro-North Railroad officials said.

Perez said witnesses on the passenger platform told detectives that Newvine apparently was worried she was going to miss her train because she was on the wrong side of the station.

"They told her to take the stairs and cross over using the overhead (Unquowa Road) pedestrian bridge, but she panicked and decided to cross over on the tracks instead," he said. "But when she got to the other side she realized she couldn't hoist herself up onto the platform."

Perez said the train engineer saw the woman and began sounding the train's horn. He said she initially sought refuge in the space under the platform.

"There is a little space under the platform and she probably would have been safe if she just stayed there," Perez said. "But for some reason she left the space and went back onto the tracks and that's when she was hit by the train."

Perez said the four people were on the platform at the time "were just in disbelief with what they saw."

"For whatever reason, she decided to take a shortcut instead of taking the stairs and the bridge," he added, "and that shortcut cost her her life."