It was -12 degrees F. at 8:20 A.M. on February 8, 1951, when an explosion rocked the six-story Minerals Building (Building 12). It destroyed two floors, plunging them into darkness, damaged the adjacent tape packing plant, sent smoke through the underground tunnels of the Saint Paul Plant, and showered debris on the streets.
The explosion killed thirteen 3M employees and one truck driver making a delivery, and injured 50 others.
The next day, President Richard M. Carlton announced that a break in a propane gas supply line had caused the explosion.
The company’s greatest disaster led to revisions in training and safety procedures to prevent further accidents.