Photos by my friend R. L. Dengler taken on May 5, 1973. Images are from the aftermath of the giant explosion on April 28, 1973 of boxcars carrying ammunition for the Vietnam War. More information about the accident is found on Wikipedia. https://en.wikipedia.org/wiki/1973_Roseville_Yard_Disaster

Accounts of the accident:

"1973 Apr 28, in Roseville, CA, a huge explosion of military ordnance occurred on a trainload of bombs and ammunition headed for the Port Chicago Naval Weapons Station and then to US troops in Vietnam. Nobody was killed. 18 government-owned boxcars, each with more than 330 250-pound bombs, exploded in a daylong series of blasts."

Another account:

"A railroad accident draws the Navy's attention to the hazards caused by fires and sensitive munitions. A train loaded with bombs had just entered the yard in Roseville, CA when a fire was observed in one of the boxcars. Before the fire department could react, a massive explosion demolished the boxcar and spread the fire.

In the next few hours, 18 boxcars exploded in succession. There were no fatalities in this accident, but 48 people were injured and property damage totaled $24 Million."