Between the years of 1908 and 1911 , 87 to 150 bombings took place at work sites , including some set up by union members . The most famous one , and the only one to cause any loss of life , killed twenty employees of the Los Angeles Times , the main supporter for the open shop movement in Los Angeles , on October 1 , 1910 . The authorities arrested James B. McNamara and Ortie McManigal in Detroit , carrying dynamite in a suitcase . Both men had ties to the Ironworkers . McManigal confessed to a number of dynamitings , and named the Secretary-Treasurer of the union , John J. McNamara , as the man who directed the bombings
most famous one
Los Angeles Times bombing
International Association of Bridge, Structural, Ornamental and Reinforcing Iron Workers