Three 15-year-old girls have been arraigned after they allegedly assaulted a woman they thought was an immigrant on an MBTA train Nov. 7, Suffolk County district attorney Daniel F. Conley’s office said.

The girls — two from Dorchester, one from Mattapan — were all charged with assault and battery with a dangerous weapon and civil rights violations, Conley’s office said in a statement. Two of the girls were arraigned Nov. 9, and one was arraigned Monday. They were all released to their parents’ custody with orders to stay away from witnesses, the victim, and one another.

On Nov. 7 at around 7:40 a.m., the 49-year-old victim boarded a Massachusetts Bay Transportation Authority Red Line train at the Savin Hill Station, Conley’s office said. The teenagers allegedly mocked her accent, verbally harassed her, and told her to “go back to [her] own country.”