Los Angeles police arrested a young woman on suspicion of stabbing a Metro employee to death on a subway train at a downtown station.

Irma Monroy, 25, of Los Angeles was booked Monday for investigation of murder, the Police Department said in a statement. She also had an unrelated felony warrant for assault with a deadly weapon.

Police said the attack began with a verbal dispute aboard a Metro Red Line train in the downtown 7th Street and Metro Center station at 10:45 p.m. on Oct. 16.

“The dispute escalated and the suspect armed herself and stabbed the victim, ultimately causing his death,” the statement said.

The employee suffered wounds to his chest and died that night at a hospital, the Los Angeles County Metropolitan Transportation Authority said in a statement.

Police said a knife was recovered at the time of Monroy’s arrest, as well as a distinctive green bike seen in security camera images of the suspect.

It was not immediately known if Monroy had an attorney who could speak on her behalf. Arraignment was scheduled for Oct. 21.