What were believed to be exaggerated reports of deaths and injuries at the United States Arsenal in Lawrenceville turned out to have underestimated the ghastliness of the event.
"As soon as the cause of the explosion, which was distinctly heard in various parts of the city, became known, there was a general rush for the scene," the Pittsburgh Daily Post reported on Sept. 18, 1862, the morning after the disaster. "We went with the crowd, and found that reality for once exceeded the report."
An estimated 79 people, all but a few women or young girls, died in the disaster, "the most terrible calamity which has ever befallen our city," the Post said.
The arsenal had been founded in 1814 and government workers made and stored munitions there for the next 100 years. During the Civil War, its mostly female work force produced many kinds of artillery shells and cartridges for the Union Army.
One large structure, known as the laboratory, "was laid in ruins -- having been heaved up by the force of the explosion and then fallen in fragments, after which it caught fire and was consumed," according to the Sept. 18 edition of the competing Pittsburgh Gazette. "The building was of frame, and in a few minutes the dead bodies were seen lying in heaps, just as they had fallen when the explosion took place."
Both papers included graphic detail on the appearance of the victims. "In some parts, where the heat was intense, nothing but whitened bones could be seen," the Gazette read. A few bones and the steel bands used to stiffen their hoop skirts were all that was left of some victims.
Efforts by local physicians to treat victims and by firefighters from nearby Pittsburgh to put out the flames drew praise from the newspapers.
Not everyone, however, had come to help.
Exploding munitions had left many victims with shrapnel and gunshot wounds.
"In the side of another girl, seven Minie balls were discovered," the Gazette reported. "These balls ... were all picked out and carried off by curiosity seekers. ... A small brass tube, supposed to be a cannon primer, was picked from the heart of one of the victims. ..."
The next day's papers speculated on possible causes. "One account says it was occasioned by the explosion of a shell, a number of which, being sent off for shipment, fell and caused a concussion," the Post reported. "Others allege that it was occasioned by friction of some powder from one of three barrels unloaded upon the porch of the laboratory. ..."
"A young lady, with whom we conversed, and who was employed in the building, states that the explosion was caused by a boy, who let fall a shell which he was carrying," the Gazette said.
An Allegheny County Coroner's jury was convened two days after the explosion to look into what happened.
Witness J.R. Frick had been delivering different types of powder to the various work rooms in the laboratory where armaments were assembled that afternoon. "I saw a fire [in the] powder on the ground between the wheels of the wagon and the [laboratory] porch," he said, according to the Sept. 20 edition of the Gazette. "The powder in the roadway ... evidently ignited from the fore wheel of my wagon. ..."
He also said he recalled seeing several barrels of powder that had been left uncovered.
The fire from the loose powder spread to one of the open barrels, Mr. Frick said. When it blew up, "the action of the air cast me out of the wagon against the palings of the fence," but he was unburned and uninjured by debris.
"I was covered to a depth of 2 feet with the ruins," he said. "[I] removed myself as hastily as possible, when I was again covered with a portion of the roof of the laboratory."
The bodies of many of the victims could not be identified. Most were buried a few blocks away in Allegheny Cemetery.
The arsenal continued to operate through the Civil War and remained a government facility into the early years of the 20th century.
Located between 39th and 40th streets, it is now the site of Arsenal Park. A commemorative plaque installed in 1965 by the Historical Society of Western Pennsylvania recalls the tragedy.
Len Barcousky can be reached at firstname.lastname@example.org or 724-772-0184. The entire "Eyewitness" series can be read on www.post-gazette.com . Look for "Pittsburgh 250" on the home page under Special Reports, click on "A year-long celebration ..." then scroll down to "Pittsburgh 250: Eyewitness."