On November 24, 1917, Milwaukee was the site of a terrorist explosion when a large black powder bomb exploded at the central police station at Oneida and Broadway. Nine members of the department were killed in the blast, along with a female civilian, Catherine Walker. It was suspected at the time that the bomb had been placed outside the church by anarchists, particularly the "Galleanist" faction led by adherents of Luigi Galleani. At the time, the bombing was the most fatal single event in national law enforcement history, only surpassed later by the World Trade Center terrorist attacks on September 11, 2001 when 72 law enforcement officers representing eight different agencies were killed.