NEW YORK (AP) _ A Japanese art student lost part of her arm after falling in front of a commuter train Sunday afternoon.

The woman, 19, was in critical condition at Bellevue Hospital, where doctors were working to reattach the arm severed at mid-bicep.

The woman, a student at the School of Visual Arts, probably survived by lying in the trench that runs between the tracks, said Port Authority spokesman Alan Hicks.

``If you lie down in the middle of the tracks, the train will go over you,'' he said.

Officials were investigating why the woman fell from the platform.

The Port Authority declined to release the woman's name pending notification of her parents, who live in Japan.