French police warned people to avoid Saint Charles train station, tweeting that an operation was underway. Soldiers and police took up positions outside the station, which was evacuated.
Three police officials said one woman was stabbed to death. Two of the officials said the other woman's throat was slit. The assailant was shot dead by soldiers who were patrolling inside the station. The officials were speaking on condition of anonymity because they weren't authorized to speak publicly about the operation.
The Paris prosecutors' office said that a counter-terrorism investigation has been opened. No further details were immediately given, including the motive for the attack. Interior Minister Gerard Collomb tweeted that he would travel to the scene.
Earlier this month, four American college students were attacked with acid at the same train station in Marseille. At the time, French authorities said the assailant was suffering from a mental illness.