*** UPDATE ***
The violence erupted when a woman pulled out a sharp object and cut the arms of two men and a woman in the Jamaica Center station at Sutphin Blvd. and Archer Ave. shortly before 9 a.m., the sources said.
Police arrested the suspected slasher at the scene.
The three victims were taken to Jamaica Hospital with minor injuries. One other person was hurt but declined medical attention.
Sources said the slashing may have been sparked by straphangers bumping into each other.
Charges against the suspect were pending. Her name was not immediately released.