Two people were killed at the scene of shooting at the Mexico City's 175 subway station on Friday evening.
The gunman, Luis Felipe Hernandez Castillo, 38, fired the gun when police stopped him from writing graffitti on the subway wall, said Mexico City district attorney Miguel Angel Mancera.
The New York Times reports Hernandez Castillo killed the officer and a construction worker who tried to stop the firing. five others were wounded.
The CNN reports the gunman is facing two charge of murder and each of attempted murder, resisting arrest and disturbing the peace.
More than 1,600 police officers are patrolling the station checking guns from the passengers, The New York Times reported.