According to the Chicago Sun Times, a dispute between a couple ended in a man fatally stabbing a young woman in the neck on a train on Chicago's Red Line around 12:30 p.m. Thursday.
Authorities speculated the argument was over a child. "This is domestic in nature," First Deputy Supt. John Escalante said at a press conference, according to the Sun Times. "We're sure of that."
Authorities arrested the alleged stabber on the train platform. He did not struggle, according to WLS-TV.
June 23, 2016, 5:17 p.m. Eastern: This story has been updated.