This Month in Cal OES History: 1973 Railroad Explosion

Jan Dunbar vividly remembers a tremendous explosion at 8:07 a.m. Before Dunbar could leave his house there was a series of more explosions.

He was off-duty as Captain of the Sacramento City Fire Department that morning but immediately jumped into his vehicle and drove to within the vicinity of one of the worst railroad disasters in United States history.

On April 28, 1973, in the Southern Pacific Railroad yard near the Northern California community of Roseville, a bomb detonated in one of the boxcars creating massive explosions, huge plumes of smoke in the air, destroyed buildings and rail sections and dug huge craters in the ground. Over a period of approximately 32 hours, 18 boxcars exploded in succession. The railroad yard was essentially destroyed.

The force of the explosions was so strong that windows were shattered 3-4 miles away from the railyard. Remarkably, there were no fatalities.

“When I was there you could really feel the shock of the detonations,” said Dunbar, who lived in Citrus Heights, about four miles from Roseville, at the time of the explosion. “It’s instantaneous. Because they are bombs, when they detonate it sends out a shock wave and the shock wave is a wave because it’s traveling at the speed of sound, just like a sound barrier. So when it hits you it really hits hard.”

[pullquote align=”left” cite=”” link=”” color=”” class=”” size=””]“When I was there you could really feel the shock of the detonations. It’s instantaneous.” [/pullquote]

About an hour before the first explosion, Dunbar was told by the Citrus Heights Fire Department that one of its crews had arrived on scene after noticing smoke billowing from inside the top of one of the boxcars.

Ironically, Dunbar’s sister and brother-in-law had driven to the same neighborhood, on the same road and across from the fire station, to pick up their horses for an early-morning ride when they also noticed the smoke.

Watching from nearby, his brother-in-law remembers seeing the firefighters putting a ladder next to the boxcar and peering inside. Instead of pulling out the water hose and attempting to put out the fire, the firefighters smartly retreated.

“As they (sister and brother-in-law) pulled out and they are following the fire truck, he said they went about a quarter mile and seven minutes after eight the first explosion had exploded,” Dunbar said. “If they had been there or if the firefighters had still been on the ladder, they would’ve been killed.”

Initial reports suggested that railroad propane cars were exploding, but Dunbar wasn’t convinced once he arrived near the railyard within 20 minutes. He noticed the explosions were engulfed in smoke as opposed to more of a clear, fireball normally associated with propane blasts.

Dunbar, now an Assistant Chief in the Hazardous Materials (Hazmat) Division for the California Governor’s Office of Emergency Services (Cal OES), estimated the explosions occurred every 3-5 minutes.

Admittedly, he was amazed that, despite reports of 37 injured people, there were no deaths.

“They (firefighters) realized putting water on this thing ain’t going to solve it,” said Dunbar. “So they backed out and decided to withdraw and let it go, which was absolutely the right decision to make.”

According to multiple media accounts, the Roseville railyard incident was reportedly triggered by a hot brake shoe igniting the oak-wood floor of a Department of Defense boxcar carrying 250-pound Air Force General Purpose bombs filled with Tritonal, a mixture of 80 percent TNT and 20 percent aluminum powder typically used in several types of ordnance such as air-dropped bombs. Dunbar, though, acknowledged a cause was never officially verified.

The train was transporting bombs from the Naval Ammunition Depot in Hawthorne, Nevada, to the ship load-out port facility at the Naval Weapons State in Concord, California. All but three of the 21 boxcars containing bombs exploded.

In the late 1990s, the Union Pacific Railroad removed previously uncovered, unexploded ordnance near the Roseville railyard explosion site. Approximately 400 residents were evacuated after an Army demolition crew was summoned from Moffett Field, a joint civil-military airport in Santa Clara County, to dispose of the bomb.

“The cleanup evidently wasn’t done as efficiently as it should’ve been by Southern Pacific (in 1973),” Dunbar said. “Some of the bombs were just covered over and then when they went through many years later to realign some of the rail lines and digging down they were pulling up bombs, and so there was a big, giant cleanup a second time but it was done with tighter restraints and controls by the county.”

According to Union Pacific, the Roseville site is the largest rail facility on the West Coast and approximately 98 percent of all traffic in Northern California moves through the railyard, which originally opened in 1906 and was last renovated in 1952.

Hazmat rail safety via Cal OES can be found here.

Jonathan Gudel

Jonathan Gudel is a Public Information Officer for the California Governor's Office of Emergency Services (Cal OES). Since joining Cal OES, he has assisted in the response and recovery efforts of the Aliso Canyon Gas Leak, the state's historic drought, the Oroville Dam Emergency Spillway Incident, unprecedented winter storms in 2017, the October (Sonoma County) and December (Santa Barbara County) 2017 wildfires, and statewide wildfire siege in 2018 . Previously, he worked in the newspaper industry for 12 years.

4 thoughts on “This Month in Cal OES History: 1973 Railroad Explosion

  • April 20, 2016 at 11:22 pm

    I remember that so vividly. My mom’s house was on Villaview Dr. in Citrus Heights, the last row of houses whose backyards faced and were open to the rail yards. My grandmother was, as usual, sitting in her bedroom praying, facing the window that looked out on the rail yards. The first explosion shattered the window and showered her with glass. She was shaken, but didn’t have a scratch on her! Makes you wonder…

  • April 21, 2016 at 6:20 pm

    Interesting story. Great picture.

    • May 3, 2016 at 8:46 am

      Thanks for the comment! Glad you like the story. Let us know if there’s anything else you’d like to hear about.


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